2022/12/01 更新

写真a

セッタイ リキオ
摂待 力生
SETTAI Rikio
所属
教育研究院 自然科学系 数理物質科学系列 教授
自然科学研究科 数理物質科学専攻 教授
理学部 理学科 教授
職名
教授
外部リンク

学位

  • 博士(理学) ( 1993年3月   東北大学 )

研究キーワード

  • Solid State physics II(Magnetism・Metal Physics・Cryogenics)

  • 強相関電子系

  • 超伝導

  • 磁性

  • 高圧

  • 低温物理学

  • フェルミ面

  • ドハース・ファンアルフェン効果

  • 量子振動

  • 純良単結晶

  • 重い電子系

研究分野

  • 自然科学一般 / 磁性、超伝導、強相関系

経歴(researchmap)

  • 新潟大学   理学部 理学科   教授

    2017年4月 - 現在

      詳細を見る

  • 新潟大学   理学部 物理学科   教授

    2012年4月 - 2017年3月

      詳細を見る

  • 大阪大学   大学院理学研究科   准教授

    2007年4月 - 2012年3月

      詳細を見る

  • 大阪大学   大学院理学研究科   助教授

    1997年10月 - 2007年3月

      詳細を見る

  • 大阪大学   大学院理学研究科   助手

    1996年4月 - 1997年9月

      詳細を見る

  • 大阪大学   理学部   助手

    1994年10月 - 1996年3月

      詳細を見る

  • 筑波大学   物質工学系   助手

    1993年4月 - 1994年9月

      詳細を見る

▶ 全件表示

経歴

  • 新潟大学   理学部 理学科   教授

    2017年4月 - 現在

  • 新潟大学   自然科学研究科 数理物質科学専攻   教授

    2012年4月 - 現在

  • 新潟大学   自然科学研究科 数理物質科学専攻   教授

    2012年4月 - 現在

  • 新潟大学   物性科学   教授

    2012年4月 - 2017年3月

所属学協会

 

論文

  • Elastic Soft Mode and Electric Quadrupole Response in Excitonic Insulator Candidate (Ta0.952V0.048)(2)NiSe5: Contribution of Electron-Phonon Interaction

    Ryosuke Kurihara, Yusuke Hirose, Sumika Sano, Keisuke Mitsumoto, Atsushi Miyake, Masashi Tokunaga, Rikio Settai

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   91 ( 2 )   2022年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We performed ultrasonic measurements on (Ta0.952V0.048)(2)NiSe5 to investigate the contribution of acoustic phonons at the zone center to structural and possible excitonic transitions. The transverse elastic constant C-55 with irreducible representation B-2g exhibits softening over 90% above a transition temperature of T-s = 280 K, indicating the soft mode of corresponding TA phonons. Our analysis based on the quadrupole response indicates that the electron-phonon interaction contributes to the excitonic transition in addition to the hybridization between the conduction and valence bands if the excitonic transition is realized.

    DOI: 10.7566/JPSJ.91.024601

    Web of Science

    researchmap

  • Two-gap time reversal symmetry breaking superconductivity in noncentrosymmetric <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>LaNiC</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

    Shyam Sundar, S. R. Dunsiger, S. Gheidi, K. S. Akella, A. M. Côté, H. U. Özdemir, N. R. Lee-Hone, D. M. Broun, E. Mun, F. Honda, Y. J. Sato, T. Koizumi, R. Settai, Y. Hirose, I. Bonalde, J. E. Sonier

    Physical Review B   103 ( 1 )   2021年1月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Physical Society (APS)  

    DOI: 10.1103/physrevb.103.014511

    researchmap

    その他リンク: http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.103.014511/fulltext

  • Symmetry Lowering on the Field-Induced Commensurate Phase in CeRhIn5

    Tomoki Kanda, Koki Arashima, Yusuke Hirose, Rikio Settai, Kazuki Matsui, Toshihiro Nomura, Yoshimitsu Kohama, Yoshihiko Ihara

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   89 ( 9 )   2020年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Temperature dependence of the In-115-NMR spectra of CeRhIn5 is studied with the external magnetic fields 10 degrees off the [100] and [001] axes. Our detailed analyses confirm that the AFM3 phase breaks the four-fold spin symmetry with the commensurate ordering vector of Q = (0. 5, 0.5, 0.25). Based on the observation of anistropic hyperfine fields, we also propose the symmetry lowering of the electronic structure in the AFM3 phase.

    DOI: 10.7566/JPSJ.89.094709

    Web of Science

    researchmap

  • High-field ultrasonic study of quadrupole ordering and crystal symmetry breaking in CeRhIn_5 査読

    101   155125-1 - 155125-8   2020年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1103/PhysRevB.101.155125

    researchmap

  • Magnetic structure of Cd-doped CeIrIn5

    Beauvois, K., Qureshi, N., Tsunoda, R., Hirose, Y., Settai, R., Aoki, D., Rodiere, P., McCollam, A., Sheikin, I

    Physical Review B   2020年

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1103/PHYSREVB.101.195146

    Web of Science

    researchmap

  • Temperature-Pressure Phase Diagram of Antiferromagnet CeAl 査読

    Tsunoda Ryoma, Hirose Yusuke, Koitabashi Takuto, Sase Yoshiyuki, Kulkarni Ruta, Thamizhavel Arumugam, Dhar Sudesh Kumar, Gouchi Jun, Uwatoko Yoshiya, Settai Rikio

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   88 ( 3 )   2019年3月

  • Electronic states of CeT2X20 (T:transition metal, X=Zn and Cd) 査読

    Yusuke Hirose, Yoshitaka Suzuki, Fuminori Honda, Ruta Kulkarni, Arumugam Thamizhavel, Naomi Kawamura, Masaichiro Mizumaki, Ryohei Simokasa, Kojiro Mimura, Hiroshi Doto, Rikio Settai

    AIP Advances   8 ( 11 )   115017   2018年11月

     詳細を見る

    出版者・発行元:{AIP} Publishing  

    DOI: 10.1063/1.5043138

    researchmap

  • Unconventional superconductivity and quantum criticality in the heavy fermions CeIrSi3 and CeRhSi3 査読

    J. F. Landaeta, D. Subero, D. Catalá, S. V. Taylor, N. Kimura, R. Settai, Y. O'Nuki, M. Sigrist, I. Bonalde

    Physical Review B   97 ( 10 )   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Physical Society  

    In most strongly correlated electron systems superconductivity appears nearby a magnetic quantum critical point (QCP) which is believed to cause unconventional behaviors. In order to explore this physics, we present here a study of the heavy-fermion superconductors CeIrSi3 and CeRhSi3 carried out using a newly developed system for high-resolution magnetic penetration-depth measurements under pressure. Superconductivity in CeIrSi3 shows a change from an excitation spectrum with a line-nodal gap to one which is entirely gapful when pressure is close but not yet at the QCP. In contrast, CeRhSi3 does not possess a T=0 quantum phase transition and the superconducting phase remains for all accessible pressures with a nodal gap. Combining both results suggests that in these compounds unconventional superconducting behaviors are rather connected with the coexisting antiferromagnetic order. This study provides another viewpoint on the interplay of superconductivity, magnetism, and quantum criticality in CeIrSi3 and CeRhSi3 and maybe in other heavy fermions.

    DOI: 10.1103/PhysRevB.97.104513

    Web of Science

    Scopus

    researchmap

  • 空間反転対称性の破れた重い超伝導物質CeIrSi<sub>3</sub>の内殻光電子分光線二色性による4f電子軌道対称性の測定

    門野 利治, 東谷 篤志, 山崎 篤志, 藤原 秀紀, 関山 明, 玉作 賢治, 矢橋 牧名, 石川 哲也, 摂待 力生, 今田 真, 森本 千香子, 阪本 紘平, 小林 慶行, 寺島 大貴, 金井 惟奈, 濱本 諭, 中川 広野, 久我 健太郎

    日本物理学会講演概要集   73 ( 0 )   1513 - 1513   2018年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人 日本物理学会  

    DOI: 10.11316/jpsgaiyo.73.1.0_1513

    CiNii Article

    researchmap

  • Quasi-two-dimensional Fermi surfaces with localized f electrons in the layered heavy-fermion compound CePt2In7 査読

    K. Goetze, Y. Krupko, J. A. N. Bruin, J. Klotz, R. D. H. Hinlopen, S. Ota, Y. Hirose, H. Harima, R. Settai, A. McCollam, I. Sheikin

    PHYSICAL REVIEW B   96 ( 7 )   2017年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report measurements of the de Haas-van Alphen effect in the layered heavy-fermion compound CePt2In7 in high magnetic fields up to 35 T. Above an angle-dependent threshold field, we observed several de Haas-van Alphen frequencies originating from almost ideally two-dimensional Fermi surfaces. The frequencies are similar to those previously observed to develop only above a much higher field of 45 T, where a clear anomaly was detected and proposed to originate from a change in the electronic structure [M. M. Altarawneh et al., Phys. Rev. B 83, 081103 (2011)]. Our experimental results are compared with band structure calculations performed for both CePt2In7 and LaPt2In7, and the comparison suggests localized f electrons in CePt2In7. This conclusion is further supported by comparing experimentally observed Fermi surfaces in CePt2In7 and PrPt2In7, which are found to be almost identical. The measured effective masses in CePt2In7 are only moderately enhanced above the bare electron mass m(0), from 2m(0) to 6m(0).

    DOI: 10.1103/PhysRevB.96.075138

    Web of Science

    researchmap

  • Characteristic Physical Properties of the Non-Kramers Gamma(3) Ground State in PrPt2Cd20 査読

    Yusuke Hirose, Tetsuya Takeuchi, Hiroshi Doto, Fuminori Honda, Atsushi Miyake, Masashi Tokunaga, Daichi Yoshizawa, Takanori Kida, Masayuki Hagiwara, Yoshinori Haga, Rikio Settai

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   86 ( 7 )   2017年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The 4f crystalline electric field (CEF) of the Pr3+ ion of PrPt2Cd20 with a cubic crystal structure has been studied by measuring its high-field magnetization up to 45 T, specific heat in a wide temperature range in magnetic fields, and electrical resistivity. Magnetization curves for the magnetic field along the [100] and [110] directions show metamagnetic-like features at approximately 1.5 and 15 T, respectively. The specific heat shows a Schottky peak centered at 2.4 K. These experimental results were explained well by the CEF scheme with the non-Kramers Gamma(3) doublet ground state with a small overall CEF splitting energy of about 40 K. The specific heat also shows another broad peak below 1K with an associated entropy release of R ln 2. This peak was interpreted by a split of the Gamma(3) doublet ground state with an energy of Delta = 0.4 K. These results suggest that the local symmetry of the Pr site is lowered from a cubic one. The possible reasons for this symmetry lowering are discussed.

    DOI: 10.7566/JPSJ.86.074711

    Web of Science

    researchmap

  • Enhancement of Tc in CeIr(In1-xCdx)5 studied by In-NQR 査読

    Mitsuharu Yashima, Kyohei Tani, Kazuhiro Nishimoto, Hidekazu Mukuda, Yoshio Kitaoka, Fuminori Honda, Rikio Settai, Yoshichika O'Nuki

    Journal of Physics: Conference Series   807 ( 5 )   2017年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:Institute of Physics Publishing  

    We report on superconducting nature under pressure in CeIr(In1-xCdx)5 by In-Nuclear-Quadrupole-Resonance (NQR) studies. In CeIr(In0.925Cd0.075)5, the inhomogeneous antiferromagnetic order at TN ∼ 2.3 K is induced by Cd-dopants and superconductivity disappears at ambient pressure. However, the measurements of a nuclear-spin-lattice-relaxation rate 1/T1 have revealed that the superconductivity suddenly occurs above 2.1 GPa. It is observed that the superconducting gap is enhanced in the Cd-doped sample, indicating that the Cd-doping induces the strong coupling superconductivity leading to the enhancement of Tc in the CeIrIn5 system. Furthermore, we found that the residual density of states at the Fermi level increases with increasing pressure, suggesting that the superconducting nature of CeIrIn5 is quite different from those of CeCoIn5 and CeRhIn5.

    DOI: 10.1088/1742-6596/807/5/052004

    Web of Science

    Scopus

    researchmap

  • Determination of the magnetic structure of CePt2In7 by means of neutron diffraction 査読

    M. Raba, E. Ressouche, N. Qureshi, C. V. Colin, V. Nassif, S. Ota, Y. Hirose, R. Settai, P. Rodiere, I. Sheikin

    PHYSICAL REVIEW B   95 ( 16 )   2017年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The magnetic structure of the heavy fermion antiferromagnet CePt2In7 is determined using neutron diffraction. We find a magnetic wave vector q(M) = (1/2,1/2,1/2), which is temperature independent up to T-N = 5.5 K. A staggered moment of 0.45(1)mu(B) at 2 K resides on the Ce ion. The nearest-neighbor moments in the tetragonal basal plane are aligned antiferromagnetically. The moments rotate by 90 degrees. from one CeIn3 plane to another along the c axis. A much weaker satellite peak with an incommensurate magnetic wave vector q(M) = (1/2,1/2,0.47) seems to develop at low temperature. However, the experimental data available so far are not sufficient to draw a definitive conclusion about the possible coexistence of commensurate and incommensurate magnetic structures in this material.

    DOI: 10.1103/PhysRevB.95.161102

    Web of Science

    researchmap

  • Single crystal growth and electronic state of new compounds RPt2Cd20 ( R = La-Nd, Sm) 査読

    Hiroshi Doto, Yusuke Hirose, Fuminori Honda, Tetsuya Takeuchi, Yoshinori Haga, Rikio Settai

    JOURNAL OF ALLOYS AND COMPOUNDS   693   332 - 338   2017年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    We succeeded in growing five new single crystalline compounds RPt2Cd20 (R = La, Ce, Pr, Nd, and Sm) by the Cd self-flux method. These compounds are found to crystallize in the cubic CeCr2Al20-type crystal structure by the X-ray diffraction using single crystals. We measured the electrical resistivity, magnetic properties, and specific heat for all compounds. The resistivity for R = Ce, Nd, and Sm indicates an abrupt decrease, which might correspond to a magnetic transition. It is suggested that the ground state of CePt2Cd20 is Gamma(7) doublet from the magnetization measurement. The magnetization of PrPt2Cd20 shows a metamagnetic behavior at 1.6 T in the paramagnetic state, which could be due to the crystalline electric field effect with non-Kramers Gamma(3) doublet or Gamma(1) singlet ground state. The contribution of optical phonon modes to the lattice specific heat is discussed in LaPt2Cd20. (C) 2016 Elsevier B. V. All rights reserved.

    DOI: 10.1016/j.jallcom.2016.09.077

    Web of Science

    researchmap

  • Three-dimensional critical phase diagram of the Ising antiferromagnet CeRh2Si2 under intense magnetic field and pressure 査読

    W. Knafo, R. Settai, D. Braithwaite, S. Kurahashi, D. Aoki, J. Flouquet

    PHYSICAL REVIEW B   95 ( 1 )   2017年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Using novel instrumentation to combine extreme conditions of intense pulsed magnetic field up to 60 T and high pressure up to 4 GPa, we have established the three-dimensional (3D) magnetic field-pressure-temperature phase diagram of a pure stoichiometric heavy-fermion antiferromagnet (CeRh2Si2). We find a temperature and pressure-dependent decoupling of the critical and pseudometamagnetic fields at the borderlines of antiferromagnetism and strongly-correlated paramagnetism. This 3D phase diagram is representative of a class of heavy-fermion Ising antiferromagnets, where long-range magnetic ordering is decoupled from a maximum in the magnetic susceptibility. The combination of extreme conditions enabled us to characterize different quantum phase transitions, where peculiar quantum critical properties are revealed. The interest to couple the effects of magnetic field and pressure on quantum-critical correlated-electron systems is stressed.

    DOI: 10.1103/PhysRevB.95.014411

    Web of Science

    researchmap

  • Valence State in CeIrIn5 at High Magnetic Fields of up to 42T 査読

    Yasuhiro H. Matsuda, Taku T. Terashima, Koichi Kindo, Ryoma Tsunoda, Rikio Settai, Naomi Kawamura, Masaichiro Mizumaki, Toshiya Inami

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   85 ( 11 )   2016年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    High-magnetic-field X-ray absorption spectroscopy of the heavy-fermion compound CeIrIn5 has been conducted to clarify the valence state of Ce at the metamagnetic transition. The field-induced change in the X-ray absorption spectrum near the Ce-L-3 edge is found to be smaller than the resolution limit of the measurement, suggesting that no field-induced valence change larger than 0.005 takes place at 2K up to 42 T.

    DOI: 10.7566/JPSJ.85.115001

    Web of Science

    researchmap

  • High-quality single crystal growth and strongly correlated electronic states in rare earth and actinide compounds 査読

    Yoshichika Onuki, Fuminori Honda, Yusuke Hirose, Rikio Settai, Tetsuya Takeuchi

    REPORTS ON PROGRESS IN PHYSICS   79 ( 11 )   2016年11月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We review the nature of strongly correlated electronic states in rare earth and actinide compounds, focusing on localized versus itinerant electronic states in CeRhIn5, quantum critical phenomena in YbIr2Zn20, residual resistivity in CeCu6, metamagnetism in heavy fermion compounds, and unconventional superconductivity in CeIrSi3 without inversion symmetry in the crystal structure, emphasizing that sample quality is essentially important to clarify the characteristic features for the heavy fermion compounds.

    DOI: 10.1088/0034-4885/79/11/114501

    Web of Science

    researchmap

  • New heavy-fermion antiferromagnet UPd2Cd20 査読

    Yusuke Hirose, Hiroshi Doto, Fuminori Honda, Dexin Li, Dai Aoki, Yoshinori Haga, Rikio Settai

    JOURNAL OF PHYSICS-CONDENSED MATTER   28 ( 42 )   2016年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We succeeded in growing a new high quality single crystal of a ternary uranium compound UPd2Cd20. From the electrical resistivity, magnetization, magnetic susceptibility, and specific heat experiments, UPd2Cd20 is found to be an antiferromagnetic heavy-fermion compound with the Neel temperature T-N = 5 K and exhibits the large electronic specific heat coefficient. exceeding 500 mJ (K-2.mol)(-1). This compound is the first one that exhibits the magnetic ordering with the magnetic moments of the U atom in a series of UT2X20 (T: transition metal, X = Al, Zn, Cd). UPd2Cd20 shows typical characteristic features in heavy-fermion systems such as a broad maximum in the magnetic susceptibility at T-chi max and a large coefficient A of T-2 term in the resistivity.

    DOI: 10.1088/0953-8984/28/42/425601

    Web of Science

    researchmap

  • First-Order Structural Change Accompanied by Yb Valence Transition in YbInCu4 査読

    Satoshi Tsutsui, Kunihisa Sugimoto, Ryoma Tsunoda, Yusuke Hirose, Takeshi Mito, Rikio Settai, Masaichiro Mizumaki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   85 ( 6 )   2016年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    A diffraction experiment using high-energy X-rays was carried out on YbInCu4. Below the Yb valence transition temperature, the splitting of Bragg peaks was detected in high-order reflections. No superlattice reflections accompanying the valence ordering were found below the transition temperature. These experimental findings indicate that a structural change from a cubic structure to a tetragonal structure without valence ordering occurs at the transition temperature. Such a structural change free from any valence ordering is difficult to understand only in terms of Yb valence degrees of freedom. This means that the structural change may be related to electronic symmetries such as quadrupolar degrees of freedom as well as to the change in Yb valence.

    DOI: 10.7566/JPSJ.85.063602

    Web of Science

    researchmap

  • Test of Spontaneous Magnetization of Non-centrosymmetric Superconductor LaIrSi3 査読

    Daichi Kawakatsu, Akihiko Sumiyama, Jun Gouchi, Akira Yamaguchi, Gaku Motoyama, Yusuke Hirose, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   85 ( 2 )   2016年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The magnetization change Delta M at the superconducting transition of LaIrSi3 has been measured in various magnetic fields H. The observed Delta M in H = 0 is within the range of the Meissner effect induced by the possible residual field, suggesting that the spontaneous magnetization, if it exists, is below the experimental accuracy. This result is in agreement with the results of mu SR experiments, in which no spontaneous magnetic field has been observed in the superconducting state.

    DOI: 10.7566/JPSJ.85.025002

    Web of Science

    researchmap

  • Pressure cell for transport measurements under high pressure and low temperature in pulsed magnetic fields 査読

    Daniel Braithwaite, William Knafo, Rikio Settai, Dai Aoki, Shuhei Kurahashi, Jacques Flouquet

    REVIEW OF SCIENTIFIC INSTRUMENTS   87 ( 2 )   2016年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We present a new specially designed pressure cell and technique adapted for resistivity measurements in pulsed magnetic fields up to 60 T at pressures up to at least 4 GPa, and temperatures down to 1.5 K. We show that heating effects during the pulse are acceptable (less than 1 K) and can be corrected allowing reliable temperature dependences of the magnetoresistance to be obtained. We illustrate the performance with a study of the phase diagram of the heavy fermion antiferromagnet CeRh2Si2. (C) 2016 AIP Publishing LLC.

    DOI: 10.1063/1.4941714

    Web of Science

    researchmap

  • Specific heat in high magnetic fields and magnetic phase diagram of CePt2In7 査読

    Y. Krupko, A. Demuer, S. Ota, Y. Hirose, R. Settai, I. Sheikin

    PHYSICAL REVIEW B   93 ( 8 )   2016年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report specific heat measurements on a high-quality single crystal of the heavy-fermion compound CePt2In7 in magnetic fields up to 27 T. The zero-field specific heat data above the Neel temperature, T-N, suggest a moderately enhanced value of the electronic specific heat coefficient gamma = 180 mJ/K-2 mol. For T &lt; T-N, the data at zero applied magnetic field are consistent with the existence of an anisotropic spin-density wave opening a gap on almost the entire Fermi surface, suggesting extreme two-dimensional electronic and magnetic structures for CePt2In7. T-N is monotonically suppressed by magnetic field applied along the c axis. When a field is applied parallel to the a axis, T-N first increases at low field up to about 10 T and then decreases monotonically at a higher field. The magnetic phase diagram based on specific heat measurements suggests that a field-induced quantum critical point is likely to occur slightly below 60 T for both principal orientations of the magnetic field.

    DOI: 10.1103/PhysRevB.93.085121

    Web of Science

    researchmap

  • Search for spontaneous magnetization in noncentrosymmetric superconductors 査読

    A. Sumiyama, D. Kawakatsu, J. Gouchi, I. Kawasaki, A. Yamaguchi, G. Motoyama, Y. Hirose, R. Settai, Y. Onuki

    TMU INTERNATIONAL SYMPOSIUM ON NEW QUANTUM PHASES EMERGING FROM NOVEL CRYSTAL STRUCTURE   683   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We have measured the magnetization of two noncentrosymmetric superconductors: Ir2Ga9 and CePt3Si using a SQUID magnetometer, neither of which has been tested for the time-reversal symmetry in the superconducting state. For Ir2Ga9, the magnetization change Delta M below the superconducting transition temperature T-c similar to 2.2 K was smaller than 10(-5) G in zero magnetic field, suggesting that Delta M originates in the Meissner effect induced by the possible residual field. When CePt3Si was cooled in zero magnetic field, Delta M along the c axis first decreased below T-c(+) similar to 0.75 K (high-T-c phase) and then increased below T-c(-) similar to 0.45 K (bulk superconducting phase). Since this behavior cannot be explained by the Meissner effect, it may be a sign of a spontaneous magnetization.

    DOI: 10.1088/1742-6596/683/1/012029

    Web of Science

    researchmap

  • 重い電子系化合物CeRhIn<sub>5</sub>の圧力下In-NQRによる研究

    八島 光晴, 道添 竜治, 椋田 秀和, 北岡 良雄, 宍戸 寛明, 摂待 力男, 大貫 惇睦

    日本物理学会講演概要集   71   2100 - 2100   2016年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人 日本物理学会  

    <p>重い電子系化合物CeRhIn_5_は常圧では反強磁性体(T_N_ = 3.8 K)で、2GPa以上の圧力下では超伝導が発現する。常圧ではらせん状の磁気構造(不整合)を有しており、圧力下においても中性子散乱実験(単結晶)やNQR法(粉末試料)によって研究されてきた。NQR測定では、右図のように1.7GPaで不整合から不整合な磁気構造へと変わることが観測されたが、単結晶試料を用いた中性子散乱実験では整合な反強磁性を確認できておらず、それぞれの測定で結果が一致していなかった。今回我々は本質的な磁気構造をNQR法で調べるため、単結晶試料を用いて測定を行った。</p>

    DOI: 10.11316/jpsgaiyo.71.2.0_2100

    CiNii Article

    researchmap

  • 20pPSB-4 CeIr(In_<1-x>Cd_x)_5の強磁場磁化測定

    角田 竜馬, 広瀬 雄介, 松田 康弘, 金道 浩一, 摂待 力生

    日本物理学会講演概要集   71   2109 - 2109   2016年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.71.1.0_2109

    CiNii Article

    CiNii Books

    researchmap

  • 20pPSB-1 重い電子系化合物CeRhIn_5の圧力下における不整合反強磁性のIn-NQRによる研究

    道添 竜治, 八島 光晴, 椋田 秀和, 北岡 良雄, 宍戸 寛明, 摂待 力男, 大貫 惇睦

    日本物理学会講演概要集   71   2106 - 2106   2016年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.71.1.0_2106

    CiNii Article

    CiNii Books

    researchmap

  • 20pPSB-2 重い電子系CeIrIn_5の強磁場中のCe価数II

    松田 康弘, 寺島 拓, 摂待 力生, 河村 直己, 水牧 仁一朗, 稲見 俊哉

    日本物理学会講演概要集   71   2107 - 2107   2016年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.71.1.0_2107

    CiNii Article

    CiNii Books

    researchmap

  • 19pBL-8 PrPt_2Cd_<20>の強磁場磁化II

    広瀬 雄介, 土塔 寛, 摂待 力生, 竹内 徹也, 本多 史憲, 芳賀 芳範, 三宅 厚志, 徳永 将史, 吉澤 大智, 木田 孝則, 萩原 政幸, Aoki D.

    日本物理学会講演概要集   71   2012 - 2012   2016年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.71.1.0_2012

    CiNii Article

    CiNii Books

    researchmap

  • 19pBL-9 PrPt_2Cd_<20>の比熱測定による結晶場基底状態の研究

    竹内 徹也, 広瀬 雄介, 土塔 寛, 本多 史憲, 摂待 力生

    日本物理学会講演概要集   71   2013 - 2013   2016年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.71.1.0_2013

    CiNii Article

    CiNii Books

    researchmap

  • 22aPS-47 新しい重い電子系反強磁性体UPd_2Cd_<20>の電子状態

    土塔 寛, 広瀬 雄介, 本多 史憲, 青木 大, 芳賀 芳範, 三宅 厚志, 徳永 将史, 摂待 力生

    日本物理学会講演概要集   71   2439 - 2439   2016年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.71.1.0_2439

    CiNii Article

    CiNii Books

    researchmap

  • 22aBM-11 重い電子系反強磁性体CeAl_2の圧力下de Haas-van Alphen効果IV

    佐瀬 芳行, 広瀬 雄介, 本多 史憲, 青木 大, 摂待 力生

    日本物理学会講演概要集   71   2370 - 2370   2016年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.71.1.0_2370

    CiNii Article

    CiNii Books

    researchmap

  • Crossover Phase Diagram and Electronic State in the Heavy-Fermion Metamagnets UIr2Zn20 and UCo2Zn20 査読

    Yusuke Hirose, Tetsuya Takeuchi, Fuminori Honda, Shingo Yoshiuchi, Masayuki Hagiwara, Etsuji Yamamoto, Yoshinori Haga, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   84 ( 7 )   2015年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Crossover phase diagrams in the magnetic field versus temperature (H-T) plane of the nonmagnetic heavy-fermion metamagnets UT2Zn20 (T:Ir, Co) are studied by measuring the magnetic and electronic transport properties. The crossover phase diagrams of UIr2Zn20 and UCo2Zn20 are composed of a low-magnetic-field region (LFR) and a high-magnetic-field region (HFR), which are characterized by magnetic properties and the Hall effect, respectively. The LFR is found to form a closed area in the H-T plane, which is a quite different feature from the conventional uranium heavy-fermion compounds and the first observation in uranium compounds. From the drastic anomaly in the Hall effect at a metamagnetic field of UIr2Zn20, it is found that the metamagnetic behavior in UIr2Zn20 corresponds to a crossover from the heavy-fermion state to the field-induced ferromagnetic or polarized paramagnetic state accompanied by the reconstruction or topology change of Fermi surfaces. In UCo2Zn20, on the other hand, no sign of abrupt change in the electronic state at the metamagnetic field is observed. These contrastive crossover phase diagrams and the electronic state changes at the metamagnetic field are due to the different hybridization strengths between the 5 f electrons of U atoms and the d electrons of Ir and Co atoms, leading to the differences in magnetic correlation and crystalline electric field ground state or the degree of itinerancy of 5 f electrons.

    DOI: 10.7566/JPSJ.84.074704

    Web of Science

    researchmap

  • Magnetization measurements of non-centrosymmetric superconductor LaPt3Si: Construction of low temperature magnetometers with the SQUID and Hall sensor 査読

    Takumi Fujisawa, Akira Yamaguchi, Gaku Motoyama, Daichi Kawakatsu, Akihiko Sumiyama, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    JAPANESE JOURNAL OF APPLIED PHYSICS   54 ( 4 )   2015年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We report magnetization of a non-centrosymmetric superconductor, LaPt3Si below 0.6 K up to 200 Oe. The home-made SQUID and Hall sensor magnetometers that operate below 1 K were constructed for this purpose. Although the SQUID magnetometer is more sensitive than the Hall sensor's one, it was found not to work correctly for the rapid magnetization change of LaPt3Si below 0.4 K. The Hall sensor magnetometer, in contrast, can properly detect magnetization jumps in the M-H curve of the superconducting state. The observed flux jumps are probably related to the interfusion of the mixed state of the LaPt3Si that is observed in the mu SR measurements. (C) 2015 The Japan Society of Applied Physics

    DOI: 10.7567/JJAP.54.048001

    Web of Science

    researchmap

  • Large Cyclotron Effective Mass Detected by de Haas-van Alphen Effect in YbCu2Si2 査読

    Dai Aoki, Fuminori Honda, Yoshiya Homma, DeXin Li, Rikio Settai, Hisatomo Harima, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   84 ( 3 )   2015年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    De Haas-van Alphen experiments were performed on the valence fluctuation compound YbCu2Si2. For the field direction close to the c-axis in the tetragonal structure, a very large cyclotron effective mass of 43m(0) was detected on branch beta, which corresponds to the nearly cylindrical Fermi surface. This mass is one of the largest cyclotron masses detected experimentally in Yb compounds.

    DOI: 10.7566/JPSJ.84.035002

    Web of Science

    researchmap

  • Spontaneous Magnetization of Non-centrosymmetric Superconductor LaNiC2 査読

    Akihiko Sumiyama, Daichi Kawakatsu, Jun Gouchi, Akira Yamaguchi, Gaku Motoyama, Yusuke Hirose, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   84 ( 1 )   2015年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have measured the magnetization of single crystals of the non-centrosymmetric superconductor LaNiC2, which is considered to break time-reversal symmetry by mu SR measurements. Below the transition temperature T-c similar to 3K, the emergence of magnetization on the order of 10(-5) G is observed in zero magnetic field along the c-axis but not along the a-axis. This spontaneous magnetization is larger than the Meissner effect induced by the possible residual field and did not change after applying magnetic fields of up to 15 mOe or after warming to room temperature. The results that the direction is related to the lack of inversion symmetry and that the magnitude is sensitive to the crystallinity of the sample suggest some analogy with pyroelectricity.

    DOI: 10.7566/JPSJ.84.013702

    Web of Science

    researchmap

  • Single crystal growth and electronic state of UPd2Cd20 査読

    Hiroshi Doto, Yusuke Hirose, Fuminori Honda, Dexin Li, Yoshiya Homma, Dai Aoki, Rikio Settai

    20TH INTERNATIONAL CONFERENCE ON MAGNETISM, ICM 2015   75   56 - 61   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    We succeeded in growing single crystals of UPd2Cd20 by the Cd self-flux method. This compound crystallizes in the cubic CeCr2Al20-type structure. From the low-temperature electrical resistivity and Kadowaki-Woods relation, the electronic specific heat coefficient. is estimated to be about 400 mJ/mol . K-2. The magnetic susceptibility of UPd2Cd20 indicates a broad maximum at 6.6 K and a rapid decrease at 5.0 K, which correspond to the formation of the heavy fermion state and the antiferromagnetic transition, respectively. These experimental results strongly suggest that UPd2Cd20 is a new heavy fermion antiferromagnet.

    DOI: 10.1016/j.phpro.2015.12.009

    Web of Science

    researchmap

  • Themal Expansion and Magnetostriction of YbAuCu<inf>4</inf> 査読

    Tetsuya Tkeuchi, Yusuke Hirose, Ryoma Tsunoda, Fuminori Honda, Rikio Settai

    Physics Procedia   75   460 - 467   2015年

     詳細を見る

    掲載種別:研究論文(国際会議プロシーディングス)  

    © 2015 The Authors. Published by Elsevier B.V. Precise thermal expansion and magnetostriction measurements were performed on the heavyfermion compound YbAuCu4 in order to examine the crossover valence transition at TV which was proposed by the nuclear magnetic resonance measurements. The temperature dependence of the thermal expansion coefficient α under magnetic fields shows a broad peak, which shifts to higher temperatures with increasing magnetic fields. The corresponding linear thermal expansion Δℓ/ℓ parallel to the magnetic field of 7.0 T shows a marked decrease below about 10 K, indicating a contraction of sample length at low temperatures. These results are discussed in relation to the observed temperature dependence of the nuclear quadrupole frequency νQ under magnetic fields.

    DOI: 10.1016/j.phpro.2015.12.057

    Scopus

    researchmap

  • Themal Expansion and Magnetostriction of YbAuCu4 査読

    Tetsuya Takeuchi, Yusuke Hirose, Ryoma Tsunoda, Fuminori Honda, Rikio Settai

    20TH INTERNATIONAL CONFERENCE ON MAGNETISM, ICM 2015   75   460 - 467   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Precise thermal expansion and magnetostriction measurements were performed on the heavy-fermion compound YbAuCu4 in order to examine the crossover valence transition at T-v which was proposed by the nuclear magnetic resonance measurements. The temperature dependence of the thermal expansion coefficient a under magnetic fields shows a broad peak, which shifts to higher temperatures with increasing magnetic fields. The corresponding linear thermal expansion Delta l/l parallel to the magnetic field of 7.0 T shows a marked decrease below about 10 K, indicating a contraction of sample length at low temperatures. These results are discussed in relation to the observed temperature dependence of the nuclear quadrupole frequency nu(Q) under magnetic fields.

    DOI: 10.1016/j.phpro.2015.12.057

    Web of Science

    researchmap

  • Single Crystal Growth and Electronic State of UPd<inf>2</inf>Cd<inf>20</inf> 査読

    Hiroshi Doto, Yusuke Hirose, Fuminori Honda, Dexin Li, Yoshiya Homma, Dai Aoki, Rikio Settai

    Physics Procedia   75   56 - 61   2015年

     詳細を見る

    掲載種別:研究論文(国際会議プロシーディングス)  

    © 2015 The Authors. Published by Elsevier B.V. We succeeded in growing single crystals of UPd2Cd20 by the Cd self-flux method. This compound crystallizes in the cubic CeCr2Al20-type structure. From the low-temperature electrical resistivity and Kadowaki-Woods relation, the electronic specific heat coefficient γ is estimated to be about 400mJ/mol ·K2. The magnetic susceptibility of UPd2Cd20 indicates a broad max-imum at 6.6K and a rapid decrease at 5.0K, which correspond to the formation of the heavy fermion state and the antiferromagnetic transition, respectively. These experimental results strongly suggest that UPd2Cd20 is a new heavy fermion antiferromagnet.

    DOI: 10.1016/j.phpro.2015.12.009

    Scopus

    researchmap

  • Anisotropy of the superconducting upper critical field and antiferromagnetism in pressure-induced superconductor CePt2In7 査読

    Shuhei Kurahashi, Shunpei Ota, Shun Tomaru, Yusuke Hirose, Rikio Settai

    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS 2014 (SCES2014)   592   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    CePt2In7 is an antiferromagnet with T-N = 5.4 K, which shows pressure-induced superconductivity at transition temperature T-c = 2.1K around a critical pressure P-c = 3.2GPa. We have investigated an anisotropy of the superconducting upper critical field H-c2 in CePt2In7, which posesses two-dimensional tetragonal crystal structure and cylindrical Fermi surfaces elongated along c-axis. At 2.60GPa, initial slope of Hc(2) for H parallel to [001] is smaller than that for H parallel to [100], reflecting the two-dimensional Fermi surface of CePt2In7. However, Pauli paramagnetic suppression is strong for H parallel to [100] compared with that for H parallel to [001] in high magnetic field, and Hc(2)(0) for H parallel to [001] seems to be larger than that for H parallel to [100] at 2.60GPa in CePt2In7.

    DOI: 10.1088/1742-6596/592/1/012006

    Web of Science

    researchmap

  • X-ray absorption spectroscopy and novel electronic properties in heavy fermion compounds YbT2Zn20 (T: Rh and Ir) 査読

    Fuminori Honda, Yusuke Hirose, Atsushi Miyake, Masaichiro Mizumaki, Naomi Kawamura, Satoshi Tsutsui, Tetsu Watanuki, Shinji Watanabe, Tetsuya Takeuchi, Rikio Settai, Dai Aoki, Yoshichika Onuki

    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS 2014 (SCES2014)   592   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    YbT2Zn20 (T: Rh and Ir), which crystallizes in the cubic CeCr2Al20-type structure, is a member of the well-known heavy fermion compounds, indicating a huge electronic specific heat coefficient gamma similar or equal to 500 mJ/(K-2.mol). We have measured temperature and magnetic field dependences of Yb valence in YbT2Zn20(T: Rh and Ir) at ambient pressure by the L-III edge x-ray absorption spectroscopy in order to investigate the valence state of Yb 4f electrons in these compounds. It is revealed that the Yb valence in both compounds significantly decreases with temperature below about 100 K and increases with increasing magnetic field at low temperatures in contrast to the case of YbCo2Zn20.

    DOI: 10.1088/1742-6596/592/1/012021

    Web of Science

    researchmap

  • Single crystal growth and magnetic properties of RCu9Sn4 (R: rare earth metals) 査読

    Yusuke Hirose, Shun Tomaru, Shoko Satoh, Shunpei Ota, Shuhei Kurahashi, Tetsuya Takeuchi, Fuminori Honda, Yoshiya Homma, Dexin Li, Dai Aoki, Rikio Settai

    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS 2014 (SCES2014)   592   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We succeeded in growing single crystals of tetragonal RCu9Sn4 (R=La, Ce, Pr, and Eu) by the Sn-self-flux method for the first time, and studied the electrical and magnetic properties of these compounds. The magnetism of CeCu9Sn4 and PrCu9Sn4 indicates an Ising anisotropy with the magnetic easy axis parallel to the [001] direction. We revealed that EuCu9Sn4 shows an antiferromagnetic transition with an easy plane type magnetic anisotropy in the present single crystal study.

    DOI: 10.1088/1742-6596/592/1/012034

    Web of Science

    researchmap

  • 22aPS-55 高圧下におけるYbIr_2Zn_<20>のX線吸収測定

    本多 史憲, 広瀬 雄介, 水牧 仁一朗, 河村 直己, 筒井 智嗣, 石松 直樹, 綿貫 徹, 渡辺 真仁, 青木 大, 摂待 力生, 大貫 惇睦

    日本物理学会講演概要集   70   2147 - 2147   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_2147

    CiNii Article

    CiNii Books

    researchmap

  • 22aPS-122 空間反転対称性のない超伝導体LaPt_3Siの直流磁化測定III

    藤沢 拓実, 山口 明, 住山 昭彦, 川勝 大地, 本山 岳, 竹内 徹也, 摂待 力生, 大貫 惇睦

    日本物理学会講演概要集   70   2211 - 2211   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_2211

    CiNii Article

    CiNii Books

    researchmap

  • 22aPS-44 重い電子系化合物CeIr(In_<1-x>Cd_x)_5の圧力下In-NQR II

    八島 光晴, 谷 恭兵, 椋田 秀和, 北岡 良雄, 宍戸 寛明工, 本多 史憲, 摂待 力生, 大貫 惇睦

    日本物理学会講演概要集   70   2136 - 2136   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_2136

    CiNii Article

    CiNii Books

    researchmap

  • 22aPS-39 CeIr(In_<1-x>Cd_x)_5の圧力下電気抵抗測定

    角田 竜馬, 広瀬 雄介, 本多 史憲, 摂待 力生, 大貫 惇睦

    日本物理学会講演概要集   70   2132 - 2132   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_2132

    CiNii Article

    CiNii Books

    researchmap

  • 21pBB-10 RPt_2Cd_<20>(R=Rare Earth)の単結晶育成と電子状態の研究

    土塔 寛, 広瀬 雄介, 本多 史憲, 李 徳新, 青木 大, 竹内 徹也, 芳賀 芳範, 摂待 力生

    日本物理学会講演概要集   70   2012 - 2012   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_2012

    CiNii Article

    CiNii Books

    researchmap

  • 21aBB-4 重い電子系化合物CeRhIn_5における不整合反強磁性と超伝導のIn-NQRによる研究

    道添 竜治, 八島 光晴, 椋田 秀和, 北岡 良雄, 宍戸 寛明, 摂待 力男, 大貫 惇睦

    日本物理学会講演概要集   70   1949 - 1949   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_1949

    CiNii Article

    CiNii Books

    researchmap

  • 22aPS-42 重い電子系CeIrIn_5の強磁場中のCe価数

    松田 康弘, 寺島 拓, 摂待 力生, 河村 直己, 水牧 仁一朗, 稲見 俊哉

    日本物理学会講演概要集   70   2134 - 2134   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_2134

    CiNii Article

    CiNii Books

    researchmap

  • 18pDA-12 UPd_2Cd_<20>の単結晶育成と電子状態の研究

    土塔 寛, 広瀬 雄介, 本多 史憲, 李 徳新, 本間 佳哉, 青木 大, 摂待 力生

    日本物理学会講演概要集   70   2034 - 2034   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.2.0_2034

    CiNii Article

    CiNii Books

    researchmap

  • 17aPS-58 PrPt_2Cd_<20>の強磁場磁化

    広瀬 雄介, 土塔 寛, 摂待 力生, 竹内 徹也, 本多 史憲, 青木 大, 芳賀 芳範, 吉澤 大智, 木田 孝則, 杉山 清寛, 萩原 政幸

    日本物理学会講演概要集   70   1853 - 1853   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.2.0_1853

    CiNii Article

    CiNii Books

    researchmap

  • 17aPS-9 重い電子系化合物CeRhIn_5の不整合反強磁性と超伝導のIn-NQRによる研究

    道添 竜治, 八島 光晴, 椋田 秀和, 北岡 良雄, 宍戸 寛明, 摂待 力男, 大貫 惇睦

    日本物理学会講演概要集   70   1807 - 1807   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.2.0_1807

    CiNii Article

    CiNii Books

    researchmap

  • 17aPS-19 CeRh_2Si_2のパルス強磁場による高圧下メタ磁性の研究

    摂待 力生, 倉橋 秀平, Knafo W., Braithwaite D., 青木 大, Flouquet J.

    日本物理学会講演概要集   70   1815 - 1815   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.2.0_1815

    CiNii Article

    CiNii Books

    researchmap

  • 17aPS-18 CeRh_2Si_2の高圧ホール効果

    荒木 新吾, 恩地 太紀, 北川 俊作, 小林 達生, 宮崎 美里, 摂待 力生, 酒井 宏典

    日本物理学会講演概要集   70   1814 - 1814   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.2.0_1814

    CiNii Article

    CiNii Books

    researchmap

  • 17aPS-25 重い電子系反強磁性体CeAl_2の圧力下de Haas-van Alphen効果II

    佐瀬 芳行, 広瀬 雄介, 本多 史憲, 青木 大, 摂待 力生

    日本物理学会講演概要集   70   1821 - 1821   2015年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.2.0_1821

    CiNii Article

    CiNii Books

    researchmap

  • Fermi surface, magnetic, and superconducting properties in actinide compounds 査読

    Yoshichika Onuki, Rikio Settai, Yoshinori Haga, Yo Machida, Koichi Izawa, Fuminori Honda, Dai Aoki

    COMPTES RENDUS PHYSIQUE   15 ( 7 )   616 - 629   2014年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER  

    The de Haas-van Alphen effect, which is a powerful method to explore Fermi surface properties, has been observed in cerium, uranium, and nowadays even in neptunium and plutonium compounds. Here, we present the results of several studies concerning the Fermi surface properties of the heavy fermion superconductors UPt3 and NpPd5Al2, and of the ferromagnetic pressure-induced superconductor UGe2, together with those of some related compounds for which fascinating anisotropic superconductivity, magnetism, and heavy fermion behavior has been observed. (C) 2014 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

    DOI: 10.1016/j.crhy.2014.06.005

    Web of Science

    researchmap

  • Superconducting Characters under Pressure in Heavy Fermion Compounds CeIr(In1−xCdx)5 Studied by In-NQR 査読

    Mitsuharu Yashima, Naoki Tagami, Tatsuya Unemori, Katsuyoshi Uematsu, Hidekazu Mukuda, Yoshio Kitaoka, Fuminori Honda, Rikio Settai, Yoshichika Ōnuki

    JPS Conference Proceedings, Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)   3   011094-1 - 011094-6   2014年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.7566/JPSCP.3.011094

    researchmap

  • Drastic Change of Electronic Properties in Ce2MgSi2 and CeNiIn4 under High Pressure 査読

    Fuminori Honda, Naohisa Yoshitani, Yusuke Hirose, Kazuhiro Ishida, Takashi Maeta, Atsushi Miyake, Shigeki Tanaka, Katsuya Shimizu, Tetsuya Takeuchi, Kazuyuki Matsubayashi, Yoshiya Uwatoko, Rikio Settai, Dai Aoki, Yoshichika Onuki

    JPS Conference Proceedings, Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)   3   011082-1 - 011082-6   2014年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.7566/JPSCP.3.012026

    researchmap

  • Precise Thermal Expansion Measurements on Heavy Fermion Compounds YbT2Zn20 (T: Co, Rh, Ir) 査読

    Tetsuya Takeuchi, Shingo Yoshiuchi, Yusuke Hirose, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JPS Conference Proceedings, Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)   3   011017-1 - 011017-6   2014年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.7566/JPSCP.3.011017

    researchmap

  • Novel Electronic States of Heavy Fermion Compound YbCo2Zn20 査読

    Fuminori Honda, Yuki Taga, Yusuke Hirose, Shingo Yoshiuchi, Yoshiharu Tomooka, Masahiro Ohya, Jyunya Sakaguchi, Tetsuya Takeuchi, Rikio Settai, Yasuyuki Shimura, Toshiro Sakakibara, Ilya Sheikin, Toshiki Tanaka, Yasunori Kubo, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   83 ( 4 )   2014年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We studied the heavy fermion compound YbCo2Zn20 with an electronic specific heat coefficient gamma similar or equal to 8000 mJ/(K-2.mol) by measuring the de Haas-van Alphen (dHvA) oscillation, Hall effect, magnetic susceptibility, and magnetization at ambient pressure, as well as the electrical resistivity in magnetic fields of up to 320 kOe and at pressures of up to 5 GPa. The detected Fermi surfaces are small in volume, reflecting the small Brillouin zone based on the large cubic lattice constant a = 14.005 angstrom. The cyclotron effective masses, which were determined from the dHvA experiment, are found to be markedly reduced in magnetic fields. In other words, the detected cyclotron masses of 2.2-8.9 m(0) (m(0): the rest mass of an electron) at H-av = 117 kOe are enhanced to 100-500 m(0) at 0 kOe. By applying pressure, the heavy fermion state disappears at P-c similar or equal to 1.8 GPa and orders antiferromagnetically for P &gt; P-c. The field-induced antiferroquadrupolar phase, which is observed only for H parallel to &lt; 111 &gt; in the magnetic field range from H-Q = 60 kOe to H-Q' = 210 kOe, is found to shift to lower magnetic fields and merge with theantiferromagnetic phase at 4.5 GPa.

    DOI: 10.7566/JPSJ.83.044703

    Web of Science

    researchmap

  • Development of non-metallic diamond anvil cell and quantum oscillation measurement of CePt<inf>2</inf>ln<inf>7</inf> in a pulsed-magnet 査読

    Atsushi Miyake, Yoshimitsu Kohama, Shunpei Ohta, Yusuke Hirose, Rikio Settai, Kazuyuki Matsubayashi, Yoshiya Uwatoko, Akira Matsuo, Koichi Kindo, Masashi Tokunaga

    Journal of Physics: Conference Series   592 ( 1 )   2014年

     詳細を見る

    掲載種別:研究論文(国際会議プロシーディングス)  

    In order to combine the extreme conditions of high pressure and magnetic field, we have developed a non-metallic diamond anvil cell to avoid Joule-heating in a pulsed-magnetic field. Although the cell is deformed with loading, a maximum pressure of ∼ 8.5 GPa can be applied. Quantum oscillation measurements using tunnel diode oscillator have been performed for heavy fermion antiferromagnet CePt2In7 in a pulsed field and at ambient pressure. The detail of the pressure cell and field-induced Fermi surface changes of CePt2In7 are discussed.

    DOI: 10.1088/1742-6596/592/1/012149

    Web of Science

    Scopus

    researchmap

  • Magnetic and fermi surface properties of EuGa<inf>4</inf> 査読

    Ai Nakamura, Yuichi Hiranaka, Masato Hedo, Takao Nakama, Yasunao Miura, Hiroki Tsutsumi, Akinobu Mori, Kazuhiro Ishida, Katsuya Mitamura, Yusuke Hirose, Kiyohiro Sugiyama, Fuminori Honda, Rikio Settai, Tetsuya Takeuchi, Masayuki Hagiwara, Tatsuma D. Matsuda, Etsuji Yamamoto, Yoshinori Haga, Kazuyuki Matsubayashi, Yoshiya Uwatoko, Hisatomo Harima, Yoshichika Onuki

    Journal of the Physical Society of Japan   82 ( 10 )   2013年10月

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    We grew a high-quality single crystal EuGa4 with the tetragonal structure by the Ga self-flux method, and measured the electrical resistivity, magnetic susceptibility, high-field magnetization, specific heat, thermoelectric power and de Haas-van Alphen (dHvA) effect, together with the electrical resistivity and thermoelectric power under pressure. EuGa4 is found to be a Eu-divalent compound without anisotropy of the magnetic susceptibility in the paramagnetic state and to reveal the same magnetization curve between H ∥ [100] and [001] in the antiferromagnetic state, where the antiferromagnetic easy-axis is oriented along the [100] direction below a Néel temperature TN = 16:5 K. The magnetization curve is discussed on the basis of a simple two-sublattice model. The Fermi surface in the paramagnetic state was clarified from the results of a dHvA experiment for EuGa4 and an energy band calculation for a non-4f reference compound SrGa4, which consists of a small ellipsoidal hole-Fermi surface and a compensated cube-like electron-Fermi surface with vacant space in center. We observed an anomaly in the temperature dependence of the electrical resistivity and thermoelectric power at TCDW = 150K under 2 GPa. This might correspond to an emergence of the charge density wave (CDW). The similar phenomenon was also observed in EuAl4 at ambient pressure. We discussed the CDW phenomenon on the basis of the present peculiar Fermi surfaces. © 2013 The Physical Society of Japan.

    DOI: 10.7566/JPSJ.82.104703

    Web of Science

    Scopus

    researchmap

  • Heavy fermions and unconventional superconductivity in high-quality single crystals of rare-earth and actinide compounds 査読

    Yoshichika Onuki, Rikio Settai, Kiyohiro Sugiyama, Tetsuya Takeuchi, Fuminori Honda, Yoshinori Haga, Etsuji Yamamoto, Tatsuma D. Matsuda, Naoyuki Tateiwa, Dai Aoki, Ilya Sheikin, Hisatomo Harima

    JOURNAL OF THE KOREAN PHYSICAL SOCIETY   63 ( 3 )   409 - 415   2013年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KOREAN PHYSICAL SOC  

    The f-electron system in rare-earth and actinide compounds exhibit a variety of characteristic properties including heavy fermions and unconventional superconductivity. The Fermi surface properties in rare-earth and actinide compounds are clarified by the de Haas-van Alphen experiments on the basis of the results of energy band calculations. The effect of pressure on the electronic states of CeRhIn5, CeIrSi3, and YbIr2Zn20 is studied in magnetic fields. An electronic instability, including unconventional superconductivity, occurs at 2.4 GPa in CeRhIn5 and 2.6 GPa in CeIrSi3. An abrupt non-linear increase in the magnetization, namely, a metamagnetic behavior, is found in the heavy fermion compounds, including YbT2Zn20 (T: Co, Rh, Ir). A super-heavy fermion state with a specific heat coefficient of 10 J/(K-2 center dot mol) is realized in YbIr2Zn20 under pressure.

    DOI: 10.3938/jkps.63.409

    Web of Science

    researchmap

  • Metamagnetic Behavior and Effect of Pressure on the Electronic State in Heavy-Fermion Compound YbRh2Zn20 査読

    Fuminori Honda, Tetsuya Takeuchi, Shinichi Yasui, Yuki Taga, Shingo Yoshiuchi, Yusuke Hirose, Yoshiharu Tomooka, Kiyohiro Sugiyama, Masayuki Hagiwara, Koichi Kindo, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   82 ( 8 )   2013年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the magnetic susceptibility, high-field magnetization, magnetoresistance, specific heat, and Hall coefficient, together with the electrical resistivity under high pressures and magnetic fields, for the heavy-fermion compound YbRh2Zn20 with the cubic CeCr2Al20-type structure. The metamagnetic behavior was observed at H-m = 65 kOe for the magnetic field along the (100) direction below T-Xmax = 5.3 K, at which the temperature of the magnetic susceptibility indicates a broad maximum. The coefficient A of the T-2 dependence of electrical resistivity rho = rho(0) + AT(2) and the electronic specific heat coefficient C/T possess a broad maximum at H-m. The metamagnetic field H-m is found to decrease with increasing pressure and to become zero at a critical pressure P-c similar or equal to 5.2 GPa. Correspondingly, the A value increases drastically in magnitude, and the Fermi liquid relation is no longer satisfied at 5.2 GPa in zero magnetic field, implying a non-Fermi liquid state. On the other hand, at magnetic fields of H &gt; 20 kOe, the low-temperature resistivity exhibits a T-2 dependence even at 5.2 GPa. The A coefficient decreases rapidly with increasing magnetic field. These results indicate that an electronic state at 5.2 GPa corresponds to the quantum critical point.

    DOI: 10.7566/JPSJ.82.084705

    Web of Science

    researchmap

  • Magnetism and superconductivity in CeCu2Ge2 under high pressures and magnetic fields 査読

    Fuminori Honda, Takashi Maeta, Yusuke Hirose, Yoshichika Onuki, Atsushi Miyake, Rikio Settai

    JOURNAL OF THE KOREAN PHYSICAL SOCIETY   63 ( 3 )   345 - 348   2013年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KOREAN PHYSICAL SOC  

    We measured the electrical resistivity of CeCu2Ge2 under various high pressures and strong magnetic fields. Beyond the previous antiferromagnetic critical pressure P (c) similar to 8 GPa, the antiferromagnetic phase is found to exist at much higher pressure of 10.9 GPa even in magnetic fields up to 8 T. The pressure vs. temperature phase diagram and the magnetic field vs. temperature phase diagram under high pressure were constructed. The pressure-induced antiferromagnetic phase is still observed and coexists with pressure-induced superconductivity at 10.9 GPa.

    DOI: 10.3938/jkps.63.345

    Web of Science

    researchmap

  • Single crystal growth and various electronic states in Yb-based compounds 査読

    Yusuke Hirose, Shingo Yoshiuchi, Naoto Nishimura, Junya Sakaguchi, Kentaro Enoki, Ken Iwakawa, Yasunao Miura, Kiyohiro Sugiyama, Yoshichika Ōnuki, Rikio Settai, Tetsuya Takeuchi, Fuminori Honda, Tatsuma D. Matsuda, Etsuji Ymamoto, Yoshinori Haga, Masayuki Hagiwara

    Journal of the Korean Physical Society   62 ( 12 )   1858 - 1861   2013年7月

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    We succeeded in growing single crystals of YbTIn 5 (T: Co, Rh, Ir), YbGa 4 , YbT 2 Zn 20 (T: Co, Rh, Ir), YbPdGe, Yb 2 Pt 2 Pb, and YbPd 5 Al 2 . The electronic and magnetic properties are clarified by measuring the electrical resistivity, magnetic susceptibility, magnetization, specific heat and de Haas - van Alphen effect. © 2013 The Korean Physical Society.

    DOI: 10.3938/jkps.62.1858

    Web of Science

    Scopus

    researchmap

  • Quadrupole effects in tetragonal crystals PrCu2Si2 and DyCu2Si2 査読

    Keisuke Mitsumoto, Saori Goto, Yuichi Nemoto, Mitsuhiro Akatsu, Terutaka Goto, Nguyen D. Dung, Tatsuma D. Matsuda, Yoshinori Haga, Tetsuya Takeuchi, Kiyohiro Sugiyama, Rikio Settai, Yoshichika Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   25 ( 29 )   2013年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We have investigated quadrupole effects in tetragonal crystals of PrCu2Si2 and DyCu2Si2 by means of low-temperature ultrasonic measurements. The elastic constant C-44 of PrCu2Si2 exhibits pronounced softening below 70 K down to a Neel temperature T-N = 20 K, which is described in terms of a quadrupole susceptibility for a Gamma(5) doublet ground state and a Gamma(3) singlet first excited state located at 15.6 K in the crystalline electric field scheme. The C-44 and C-66 of DyCu2Si2 also show softening below 70 K down to T-N1 = 9.7 K. A low-lying pseudo-sextet state consisting of three Kramers doublets of Gamma(6) circle plus 2 Gamma(7) brings about softening of C-44 and C-66 in DyCu2Si2.

    DOI: 10.1088/0953-8984/25/29/296002

    Web of Science

    researchmap

  • Effect of pressure on the field-induced ordered phase in the heavy-fermion compound YbCo2Zn20 査読

    Tetsuya Takeuchi, Yuki Taga, Shingo Yoshiuchi, Masahiro Ohya, Yusuke Hirose, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE KOREAN PHYSICAL SOCIETY   62 ( 12 )   1852 - 1854   2013年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KOREAN PHYSICAL SOC  

    The effect of pressure on the field-induced ordered phase for H aEuro- aOE (c) 111 &gt; in the heavy-fermion compound YbCo2Zn20, which is presumably a field-induced antiferro-quadrupolar (FI-AFQ) phase, was investigated in the pressure range up to 4.5 GPa and under magnetic fields up to 80 kOe. When pressure is applied, the metamagnetic-like transition at H (m) =6 kOe shifts to lower fields and disappears around the quantum critical pressure P (c) similar to 1.8 GPa. A pressure-induced antiferromagnetic (PI-AFM) phase appears at pressures above about 2 GPa, and the critical field H (c) of the PI-AFM phase increases with increasing pressure. On the other hand, the transition field H (Q) of the FI-AFQ phase decreases gradually without showing any anomalous behavior around P (c) and becomes obscure around 4 GPa, where H (c) of the PI-AFM phase and H (Q) of the FI-AFQ phase become comparable. The magnetic field versus pressure, H-P, phase diagram for H aEuro- aOE (c) 111 &gt; at 0.1 K was constructed in the pressure range up to 4.5 GPa.

    DOI: 10.3938/jkps.62.1852

    Web of Science

    researchmap

  • Outbreak of Yersiniosis in Egyptian Rousette Bats (Rousettus aegyptiacus) Caused by Yersinia pseudotuberculosis Serotype 4b 査読

    S. Nakamura, S. Settai, H. Hayashidani, T. Urabe, S. Namai, Y. Une

    JOURNAL OF COMPARATIVE PATHOLOGY   148 ( 4 )   410 - 413   2013年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    This report describes an outbreak of yersiniosis in Egyptian rousette bats (Rousettus aegyptiacus) caused by Yersinia pseudotuberculosis serotype 4b. Twelve of 61 bats died between November and December 2008 or in May 2009. The bats often displayed multiple yellow white nodules in the spleen and liver. Microscopically, these consisted of focal necrosis accompanied by inflammatory cell infiltration and colonies of gram-negative bacilli. The bacterial colonies were identified immunohistochemically as T. pseudotuberculosis 04 and T. pseudotuberculosis serotype 4b was identified by bacteriological examination. Polymerase chain reaction demonstrated that the isolate harboured the virulence genes virF,inv and ypmA. YPMa is as a superantigenic toxin that is associated with acute systemic infection in man and may contribute to the virulence of Y. pseudotuberculosis in bats. (C) 2012 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jcpa.2012.07.007

    Web of Science

    researchmap

  • Electronic states in antiferromagnet UCd11 and reference compound ThCd11: studied by the de Haasvan Alphen effect 査読

    Yusuke Hirose, Yasunao Miura, Hiroki Tsutsumi, Shingo Yoshiuchi, Masahiro Ohya, Kiyohiro Sugiyama, Tetsuya Takeuchi, Hiroshi Yamagami, Etsuji Yamamoto, Yoshinori Haga, Rikio Settai, Yoshichika Onuki

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   250 ( 3 )   642 - 645   2013年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    We carried out the de Haasvan Alphen (dHvA) experiment for an antiferromagnet UCd11 and its non-5f reference compound ThCd11 to clarify the Fermi surface properties and the true electronic specific-heat coefficient of UCd11. We observed dHvA signals of both compounds and compared the experimental results with the result of theoretical band calculations. The Fermi surfaces of both compounds are found to be small and closed. The cyclotron masses obtained from the dHvA data of UCd11 are compared with those of reference compounds ThCd11, NpCd11, and LaCd11, and the value of UCd11 is estimated to be about 100mJK2mol1, which is much smaller than the 840mJK2mol1 in the previous reports. It is concluded that this large value is mainly not due to heavy quasiparticles but due to the magnetic contribution to the specific heat.

    DOI: 10.1002/pssb.201200765

    Web of Science

    researchmap

  • Heavy-fermion superconductivity and Fermi-surface properties under pressure 査読

    Yoshichika Onuki, Rikio Settai, Yasunao Miura, Hiroki Tsutsumi, Fuminori Honda, Hisatomo Harima

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   250 ( 3 )   583 - 588   2013年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    We present an overview of the Fermi-surface properties for antiferromagnets CeRh2Si2, CeIn3, CeRhIn5, and CeIrSi3, which were clarified from the de Haasvan Alphen (dHvA) experiments under strong magnetic fields up to 170kOe and high pressures up to 3GPa. A drastic change of the 4f-electronic state from a 4f-localized Fermi surface to a 4f-itinerant Fermi surface occurs in CeRh2Si2, CeIn3, and CeRhIn5 when the pressure P crosses a critical pressure Pc or P*c. Here, the Neel temperature TN disappears and the superconducting state appears at around Pc or P*c. A critical pressure P*c in CeRhIn5 is the pressure when TN is extrapolated to zero in the temperature vs. pressure phase diagram, and/or the antiferromagnetic state disappears completely even in magnetic fields. This is because the antiferromagnetic state is stable against magnetic fields, or in other words, the antiferromagnetic state recovers in magnetic fields. CeIrSi3 without inversion symmetry in the tetragonal structure is also similar to CeRhIn5 in the superconducting and Fermi-surface properties. It is characteristic that a huge upper critical field at zero temperature in superconductivity Hc2(0)similar or equal to 450 kOe is realized for H parallel to[001] in CeIrSi3 with the superconducting transition temperature Tsc=1.6K.

    DOI: 10.1002/pssb.201200913

    Web of Science

    researchmap

  • Heavy Fermion State in Antiferromagnet UCd11 査読

    Etsuji Yamamoto, Yusuke Hirose, Kentaro Enoki, Katsuya Mitamura, Kiyohiro Sugiyama, Tetsuya Takeuchi, Masayuki Hagiwara, Koichi Kindo, Yoshinori Haga, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We grew single crystals of an antiferromagnetic heavy-fermion compound UCd11 and a reference compound ThCd11, and carried out the magnetic susceptibility, high-field magnetization, and specific heat measurements in order to get more insight into the heavy fermion state which is realized in the antiferromagnetic state. The specific heat results suggest that the crystalline electric field (CEF) ground state of UCd11 is a doublet and the total splitting energy of the CEF scheme is less than 100 K. The H - T phase diagram for H parallel to &lt; 100 &gt; is approximately reproduced in the present experiments.

    DOI: 10.1143/JPSJS.81SB.SB023

    Web of Science

    researchmap

  • Anisotropic Spin Fluctuations in the Heavy Fermion Systems: Case studies of CePd5Al2 and NpPd5Al2 査読

    Hironori Sakai, Hiroyuki Chudo, Yo Tokunaga, Shinsaku Kambe, Yoshinori Haga, Filip Ronning, Eric D. Bauer, Joe D. Thompson, Yoshiya Homma, Dai Aoki, Yasunori Nakano, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    In the so-called 115 family members with chemical formulae of CeTIn5 (T=Co, Rh, Ir) and AnTGa(5) (An=U, Np, Pu), our analysis of the Knight shift and spin-lattice relaxation rates suggests that larger XY-type anisotropy in the antiferromagnetic spin fluctuations in the normal states would favor d-wave superconductivity with higher T-c. In order to examine this working hypothesis, the anisotropy ratios of antiferromagnetic fluctuations are derived from our NMR results for the superconductor NpPd5Al2 and antiferromagnet CePd5Al2, which are tetragonal compounds with a 115-related structure. CePd5Al2 shows Ising-type anisotropy, which is the same anisotropy as in the ordered state. On the other hand, NpPd5Al2 shows XY-type anisotropy just above T-c.

    DOI: 10.1143/JPSJS.81SB.SB003

    Web of Science

    researchmap

  • Multiple Metamagnetic Transitions in Antiferromagnet Yb2Pt2Pb with the Shastry-Sutherland Lattice 査読

    Ken Iwakawa, Yusuke Hirose, Kentaro Enoki, Kiyohiro Sugiyama, Tetsuya Takeuchi, Fuminori Honda, Masayuki Hagiwara, Koichi Kindo, Takehito Nakano, Yasuo Nozue, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    From the magnetization and magnetoresistance measurements, we constructed the magnetic phase diagram of Yb2Pt2Pb with the Shastry-Sutherland lattice, which consists of characteristic two phases below 1 K with many metamagnetic transitions, revealing magnetic frustrations.

    DOI: 10.1143/JPSJS.81SB.SB058

    Web of Science

    researchmap

  • Electronic and Magnetic Properties in Heavy Fermion Ferromagnet YbPdGe 査読

    Kentaro Enoki, Yusuke Hirose, Shingo Yoshiuchi, Kiyohiro Sugiyama, Fuminori Honda, Tetsuya Takeuchi, Etsuji Yamamoto, Yoshinori Haga, Masayuki Hagiwara, Koichi Kindo, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The crystal structure of YbPdGe is orthorhombic, with a large lattice constant for the b-axis. Reflecting this crystal structure, the electronic state is well conductive in the a-c plane. Magnetically YbPdGe is a ferromagnet with a Curie temperature T-C = 11.4 K, and ferromagnetic moments are most likely oriented along the b-axis. The electronic specific heat coefficient gamma = 150 mJ/(K-2.mol) and a reduced magnetic entropy at T-C suggest that YbPdGe is a heavy fermion ferromagnet.

    DOI: 10.1143/JPSJS.81SB.SB056

    Web of Science

    researchmap

  • Neutron Scattering Study on High-quality Single Crystals of Non-Centrosymmetric Heavy-Fermion Superconductor CePt3Si 査読

    Koji Kaneko, Oliver Stockert, Markos Skoulatos, Astrid Schneidewind, Tetsuya Takeuchi, Tatsuma D. Matsuda, Yoshinori Haga, Rikio Settai, Yoshichika Onuki, Naoto Metoki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    In order to get detailed insights into magnetism and its relationship with superconductivity, neutron scattering experiments were carried out on high-quality single crystals of the non-centrosymmetric heavy-fermion superconductor CePt3Si, with T-N=2.2 K and T-SC similar to 45 K. All the samples used in this study were characterised via specific heat measurements. Sharp specific heat jumps at T-sc=0.45 K, and T-N=2.2K for all samples prove the high quality of the crystal. The neutron diffraction study confirms that an antiferromagnetic peak described with the propagation vector q=(0 0 1/2) persists inside the superconducting state, with a tiny suppression of the magnetic intensity below T-sc. In contrast, an external magnetic field along the [0 0 1] direction causes a drastic change in the antiferromagnetic state; the antiferromagnetic intensity shows an enormous enhancement with increasing applied field. The magnetic intensity does not show any anomaly at B-c2, instead there exists a small inflection at around B' similar to 3.8 T where an additional phase boundary was reported. The huge increase in antiferromagnetic intensity corresponds to an increase of the staggered moment under uniform field, opposite of what is observed in ordinary antiferromagnets. These features suggest a weak coupling between magnetic and superconducting order parameters, and clearly evidence the anomalous antiferromagnetism in this compound.

    DOI: 10.1143/JPSJS.81SB.SB006

    Web of Science

    researchmap

  • Collapse and Enhancement of the Heavy Fermion State in CeCu6 under Magnetic Field and Pressure 査読

    Yusuke Hirose, Jyunya Sakaguchi, Masahiro Ohya, Masaki Matsushita, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the electrical resistivity under magnetic field and pressure and de Haas van Alphen (dHvA) oscillations in CeCu6. The A value in the Fermi liquid relation of the electrical resistivity rho = rho 0 + AT(2) and the cyclotron effective mass are reduced with increasing magnetic fields and pressures. The A value, however, becomes distinct and/or is enhanced at the metamagnetic field, especially, in a characteristic pressure region where the electronic state deviates from the heavy fermion state, for example, at 2.00 GPa.

    DOI: 10.1143/JPSJS.81SB.SB009

    Web of Science

    researchmap

  • Differential Paramagnetic Effect of Non-Centrosymmetric Superconductor LaPt3Si 査読

    G. Motoyama, M. Shiotsuki, Y. Oda, A. Yamaguchi, A. Sumiyama, T. Takeuchi, R. Settai, Y. Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report the superconducting properties of LaPt3Si poly and single crystals with non-centrosymmetric structure. We have measured ac magnetic susceptibility, chi(ac) - chi' + i chi'', under sweeping magnetic fields. On the chi', a peak ascribed to the differential paramagnetic effect DPE is observed just below critical fields, where the superconducting state of LaPt3Si collapses completely by an external magnetic field. However this DPE behavior disappears below 0.40 K. Additionally, in this temperature range, the width of the magnetic field of collapsing superconductivity becomes broader and the superconducting domains survive even in higher magnetic fields.

    DOI: 10.1143/JPSJS.81SB.SB017

    Web of Science

    researchmap

  • Characteristic Electronic State in Quasicrystal Approximants RCd6 (R: Rare Earth) 査読

    Akinobu Mori, Hisashi Ota, Shingo Yoshiuchi, Ken Iwakawa, Yuki Taga, Yusuke Hirose, Tetsuya Takeuchi, Etsuji Yamamoto, Yoshinori Haga, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the electrical resistivity, magnetic susceptibility, and specific heat in quasicrystal approximants RCd6. It was confirmed that the structural order-disorder transition of a tetrahedron with 4Cd atoms occurs at about 160 K when the lattice constant a is longer than a = 15.481 angstrom in YCd6, namely for RCd6 (R: Y, Pr, Nd, Sm, Gd, Tb, Dy and Yb). The structural transition is found to have a great influence on the low-temperature electrical resistivity.

    DOI: 10.1143/JPSJS.81SB.SB019

    Web of Science

    researchmap

  • Pressure-induced change of the antiferromagnetic structure in CeRhIn5 studied by In-NQR measurements 査読

    Mitsuharu Yashima, Hidekazu Mukuda, Yoshio Kitaoka, Hiroaki Shishido, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report a pressure-induced evolution of magnetism and superconductivity in a helical magnet CeRhIn5 with an incommensurate wave vector Q(i) = (1\2, 1\2, 0.297) through the In-115 nuclear quadrupole resonance (NQR) measurements under P. From systematic measurements of the In-115-NQR spectrum, it is suggested that the commensurate antiferromagnetic order with Q(c) = (1\2, 1\2, 1\2) is realized near an antiferromagentic quantum critical point. The homogeneous coexistence of superconductivity and the commensurate antiferromagnetism is observed from the measurements of a nuclear spin-lattice relaxation rates (1/T-1) at 1.82 GPa. The analysis for 1/T-1 data below Tc indicates that the strong coupling superconductivity is realized above an antiferromagnetic quantum critical point.

    DOI: 10.1143/JPSJS.81SB.SB013

    Web of Science

    researchmap

  • de Haas-van Alphen Effect and Fermi Surface Properties in V5Si3 査読

    Hiroki Tsutsumi, Jyunya Sakaguchi, Yasunao Miura, Tatsuma D. Matsuda, Yoshinori Haga, Tetsuya Takeuchi, Hisatomo Harima, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing high-quality single crystals of V5Si3 with a high melting point of 2010 degrees C, and carried out the electrical resistivity, specific heat, magnetic susceptibility, and the de Haas-van Alphen measurements to clarify the electronic properties. The Fermi surface is small in volume and is well explained by the result of energy band calculations. The cyclotron mass is in the range from 5.3 to 0.2m(0) (m(0): rest mass of an electron), consistent with the electronic specific heat coefficient gamma = 9.7 mJ/(K-2.mol).

    DOI: 10.1143/JPSJS.81SB.SB027

    Web of Science

    researchmap

  • Antiferromagnetic Heavy Fermion State in CeAl3 査読

    Kazuhiro Ishida, Yuki Taga, Yusuke Hirose, Ken Iwakawa, Akinobu Mori, Fuminori Honda, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the electrical resistivity of a prototype heavy fermion antiferromagnet CeAl3 in the temperature range from 0.1 K to room temperature under various magnetic fields and pressures. The heavy fermion state at ambient pressure is drastically destroyed under a small pressure and magnetic field.

    DOI: 10.1143/JPSJS.81SB.SB053

    Web of Science

    researchmap

  • Development of the Valence Fluctuation in the Nearly Divalent Compound YbCu2Ge2 under High Pressure 査読

    Atsushi Miyake, Fuminori Honda, Rikio Settai, Katsuya Shimizu, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Pressure driven valence fluctuations of a paramagnetic compound YbCu2Ge2, having the almost divalent configuration, has been investigated via the electrical resistivity (rho) measurement. Temperature dependence of the resistivity rho(T) shows typical metallic behavior expected for the non-magnetic metals at low pressure. With increasing pressure, the rho is strongly enhanced, and a broad shoulder-like anomaly appears in the rho(T) curve, as observed in the valence fluctuating system. The effective mass deduced from the rho(T) is strongly enhanced, indicating that YbCu2Ge2 changes to the heavy fermion system. The observation of the strong enhancement of the residual resistivity above 10 GPa, where the mass also starts to increase drastically, indicating the development of the valence fluctuation.

    DOI: 10.1143/JPSJS.81SB.SB054

    Web of Science

    researchmap

  • High-Quality Single Crystal Growth and Unique Electronic States under Magnetic Field and Pressure in Rare Earth and Actinide Compounds 査読

    Yoshichika Onuki, Rikio Settai, Tetsuya Takeuchi, Kiyohiro Sugiyama, Fuminori Honda, Yoshinori Haga, Etsuji Yamamoto, Tatsuma D. Matsuda, Naoyuki Tateiwa, Dai Aoki, Ilya Sheikin, Hisatomo Harima, Hiroshi Yamagami

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The f electrons in rare earth and actinide compounds exhibit variety of characteristic properties including heavy fermions and unconventional superconductivity. Fermi surface properties in rare earth and actinide compounds such as CeSn3, USi3, NpGe3 and PuIn3 are clarified by the de Haas-van Alphen experiments on the basis of the results of energy band calculations. An abrupt nonlinear increase of magnetization, namely metamagnetic behavior is found in the heavy fermion compounds including YbT2Zn20 ( T: Co, Rh, Ir). An effect of pressure on the electronic state of YbIr2Zn20 and antiferromagnets CeRhIn5 and CeIrSi3 are also studied in magnetic fields. The electronic instability including unconventional superconductivity occurs at about 2.4 GPa in CeRhIn5 and 2.6 GPa in CeIrSi3.

    Web of Science

    researchmap

  • Pressure-induced super heavy fermion state and antiferromagnetism in YbIr2Zn20 査読

    Fuminori Honda, Yuki Taga, Shinichi Yasui, Shingo Yoshiuchi, Yusuke Hirose, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We studied an effect of pressure on the electronic state of YbIr2Zn20 under magnetic fields. The heavy fermion state at ambient pressure is found to be changed into an antiferromagnetic state at pressures larger than a critical pressure P-c similar or equal to 5.2 GPa, where the electronic state indicates a super-heavy fermion state with an order of the electronic specific specific heat coefficient gamma = 20 J/(K-2.mol). The temperature dependence of the electrical resistivity shows a characteristic two-peak structure above 5.0 GPa, implying the combined phenomena between the Kondo effect and the crystalline electric field effect. At 7.6 GPa, the magnetoresistance shows a broad maximum at a critical field H-c, corresponding to a pressure-induced antiferromagnetic phase with the Neel temperature T-N = 1.4 K. T-N increases with further increasing pressure.

    DOI: 10.1143/JPSJS.81SB.SB063

    Web of Science

    researchmap

  • Characteristic Hall Coefficient in Heavy Fermion Compounds YbT2Zn20 (T : Co, Rh, Ir) 査読

    Yoshiharu Tomooka, Shingo Yoshiuchi, Yuki Taga, Tetsuya Takeuchi, Fuminori Honda, Kiyohiro Sugiyama, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the Hall coefficient in heavy fermion compounds YbT2Zn20 (T : Co, Rh, Ir) in the temperature range from 0.05 to 300 K. The Hall coefficient -R-H is found to indicate characteristic two extremals with a maximum and a minimum, reflecting a peak in the magnetic resistivity and the magnetic susceptibility.

    DOI: 10.1143/JPSJS.81SB.SB062

    Web of Science

    researchmap

  • Development of a Two-Axis Rotator in Pulsed High Magnetic Fields for a Magnetic Torque Measurement 査読

    Takanori Kida, Hideyuki Kotsuji, Junichi Nishido, Koichi Akashi, Kazuya Taniguchi, Koichi Kindo, Rikio Settai, Yoshichika Onuki, Masayuki Hagiwara

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We present a magnetic torquemeter utilizing a piezoresistive microcantilever for use in pulsed high magnetic fields. Pulsed high magnetic fields are generated with a non-destructive pulsed magnet, which has a large bore diameter (48 mm) and a large sample space size (33 mm). Since differential gears are built into the sample space of this apparatus, it is possible to change sample angles against the magnetic field direction freely. By using this apparatus, we have performed the de Haas-van Alphen (dHvA) measurement on a high-quality Pb single crystal.

    DOI: 10.1143/JPSJS.81SB.SB067

    Web of Science

    researchmap

  • Quantum Criticality and Heavy Fermion State in YbCo2Zn20 under Pressure and Magnetic Field 査読

    Yuki Taga, Shingo Yoshiuchi, Masahiro Ohya, Jyunya Sakaguchi, Yusuke Hirose, Fuminori Honda, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We studied an effect of pressure on the heavy fermion state of YbCo2Zn20 under magnetic fields. The critical pressure P-c, where the electronic state changes from the heavy fermion state to the antiferromagnetic state, is estimated to be P-c similar or equal to 1.8 GPa. The super-heavy fermion state in the P-c region is found to be strongly destroyed in magnetic fields for H parallel to &lt; 100 &gt;. The field-induced quadrupolar phase, which is most likely realized only for H parallel to &lt; 111 &gt;, is found to be robust even in the antiferromagnetic pressure region.

    DOI: 10.1143/JPSJS.81SB.SB064

    Web of Science

    researchmap

  • Electrical and Magnetic Properties of New Yb-based Compound YbPd5Al2 査読

    Yusuke Hirose, Naoto Nishimura, Kentaro Enoki, Fuminori Honda, Tetsuya Takeuchi, Kiyohiro Sugiyama, Masahiro Hagiwara, Koichi Kindo, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing a single crystal of YbPd5Al2 with the tetragonal structure. The temperature dependence of electrical resistivity and a small value of the coefficient A in the Fermi liquid relation rho = rho(0) + AT(2) suggest that the 4f-electrons are well localized. A magnetic ordering was found at T-o = 0.19 K in the specific heat measurement. On the other hand, the magnetic entropy exhibits only 0.5R ln 2 at T-o, and the specific heat shows a long tail above T-o.

    DOI: 10.1143/JPSJS.81SB.SB057

    Web of Science

    researchmap

  • Magnetic Properties of RIr2Zn20 (R : Rare Earth) with the Caged Structure 査読

    Yuki Taga, Kiyohiro Sugiyama, Kentaro Enoki, Yusuke Hirose, Ken Iwakawa, Akinobu Mori, Kazuhiro Ishida, Tetsuya Takeuchi, Masayuki Hagiwara, Koichi Kindo, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Neel temperatures in RIr2Zn20 (R: rare earth) with the cubic caged structure are found to be very low, which are below T-N=5.0 K for GdIr2Zn20. This is mainly due to the long R-R distance and R atoms are spherically surrounded by Zn atoms. The corresponding crystalline electric field (CEF) splitting energies are also small, being below 100 K.

    DOI: 10.1143/JPSJS.81SB.SB051

    Web of Science

    researchmap

  • de Haas-van Alphen Effect and Fermi Surface Properties in YbTIn5 (T : Co, Rh, Ir) and YbCoGa5 査読

    Jyunya Sakaguchi, Hiroki Tsutsumi, Yusuke Hirose, Yasunao Miura, Fuminori Honda, Hisatomo Harima, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the de Haas-van Alphen oscillation in divalent compounds YbTIn5 (T : Co, Rh, Ir) and YbCoGa5. The Fermi surfaces, which are characteristic in two kinds of nearly cylindrical Fermi surface, are approximately unchanged in these compounds and are well explained by the results of energy band calculations. The cyclotron mass is found to increase remarkably as the average lattice constant decreases from 5.4 angstrom in YbIrIn5 to 5.2 angstrom in YbCoGa5: m(c)* = 1.1m(0) in YbIrIn5 and 5.1m(0) in YbCoGa5 for dHvA branch beta(1), revealing a chemical pressure effect. There exists the hybridization between 4f electrons and conduction electrons in YbCoGa5.

    DOI: 10.1143/JPSJS.81SB.SB059

    Web of Science

    researchmap

  • Fermi Surface and Superconducting Properties of Non-centrosymmetric LaNiC2 査読

    Yusuke Hirose, Toshihiko Kishino, Jyunya Sakaguchi, Yasunao Miura, Fuminori Honda, Tetsuya Takeuchi, Etsuji Yamamoto, Yoshinori Haga, Hisatomo Harima, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81 ( 11 )   2012年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing single crystals of LaNiC2 with the non-centrosymmetric orthorhombic structure by the Czochralski method, and measured the electrical resistivity, de Haas-van Alphen effect, and specific heat to clarify the Fermi surface and superconducting properties. This compound has been studied from a viewpoint of the triplet superconducting pairing state. In the present experiment, we observed an ellipsoidal Fermi surface and a multiply-connected-pillar Fermi surface, which are split into two Fermi surfaces, reflecting the antisymmetric spin-orbit interaction based on the non-centrosymmetric crystal structure. The two ellipsoidal Fermi surfaces are split by 230 K, for example. The anisotropy of electrical resistivity and upper critical field H-c2 in superconductivity are not large for three principal directions. From the low-temperature specific heat measurement, superconductivity in LaNiC2 is explained by the framework of the BCS-superconductivity, contrary to the above arguments. The upper critical field H-c2(0), which was obtained from the specific heat under magnetic fields, is about 2 kOe.

    DOI: 10.1143/JPSJ.81.113703

    Web of Science

    researchmap

  • Possibility of Valence-Fluctuatsion-Mediated Superconductivity in Cd-Doped CeIrIn5 Probed by In NQR 査読

    M. Yashima, N. Tagami, S. Taniguchi, T. Unemori, K. Uematsu, H. Mukuda, Y. Kitaoka, Y. Ota, F. Honda, R. Settai, Y. Onuki

    PHYSICAL REVIEW LETTERS   109 ( 11 )   2012年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report on a pressure-induced evolution of exotic superconductivity and spin correlations in CeIr(In1-xCdx)(5) by means of in-nuclear-quadrupole-resonance (NQR) studies. Measurements of an NQR spectrum and nuclear-spin-lattice-relaxation rate 1/T-1 have revealed that antiferromagnetism induced by Cd doping emerges locally around Cd dopants, but superconductivity is suddenly induced at T-c = 0.7 and 0.9 K at 2.34 and 2.75 GPa, respectively. The unique superconducting characteristics with a large fraction of the residual density of state at the Fermi level which increases with T-c differ from those for anisotropic superconductivity mediated by antiferromagnetic correlations. By incorporating the pressure dependence of the NQR frequency pointing to the valence change of Ce, we suggest that unconventional superconductivity in the CeIr(In1-xCdx)(5) system may be mediated by valence fluctuations.

    DOI: 10.1103/PhysRevLett.109.117001

    Web of Science

    researchmap

  • Spin Susceptibility of CeOs4Sb12 Probed by 121Sb-NMR

    Mitsuharu Yashima, Hidekazu Mukuda, Yoshio Kitaoka, Hiroaki Shishido, Rikio Settai, Yoshichika ŌnukiMamoru Yogi, Haruo Niki, Hidekazu Mukuda, Yoshio Kitaoka, Hitoshi Sugawara, Hideyuki Sato

    J. Phys. Soc. Jpn. 81 Supplement B, SB049/1-4 (2012)   2012年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • de Haas-van Alphen effect and Fermi surface properties in rare earth and actinide compounds (Review Article) 査読

    Yoshichika Onuki, Rikio Settai

    LOW TEMPERATURE PHYSICS   38 ( 2 )   89 - 153   2012年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Fermi surface properties in rare earth (R) and actinide (An) compounds of RX3 (X: Al, Ga, In, Si, Ge, Sn, Pb), AnX(3), RTIn5 (T: transition metal), and AnTGa(5) are clarified as a function of the number of valence electrons. The electronic state can be changed by applying pressure and magnetic field. A change of Fermi surface properties associated with the metamagnetic behavior and the quantum critical point is also clarified precisely, together with the split Fermi surfaces in the non-centrosymmetric crystal structure, and the de Haas-van Alphen oscillations in the superconducting mixed state. In the quantum critical point region, the conduction electrons, or quasi-particles, are of an f-electron character, with heavy effective masses of 10-100 m(0) (m(0) is the rest mass of an electron) and condense into the unconventional (anisotropic) superconducting state. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3683408]

    DOI: 10.1063/1.3683408

    Web of Science

    researchmap

  • Electrical and Magnetic Properties of Quasicrystal Approximants RCd6 (R: Rare Earth) 査読

    Akinobu Mori, Hisashi Ota, Shingo Yoshiuchi, Ken Iwakawa, Yuki Taga, Yusuke Hirose, Tetsuya Takeuchi, Etsuji Yamamoto, Yoshinori Haga, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   81 ( 2 )   2012年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the electrical resistivity, magnetic susceptibility, magnetization, and specific heat of the quasicrystal approximants RCd6 (R: rare earth, Y-Lu) with a body-centered cubic (bcc) crystal structure. Single crystals were grown by the Cd-self flux method and annealing method. We confirmed that the structural order-disorder transition is realized at about 160K when the lattice constant a is larger than 15.481 angstrom in YCd6, namely, for R = Pr, Nd, Sm, Gd, Tb, Dy, and Yb. At lower temperatures, RCd6 compounds, except non-4f reference compounds YCd6 and LuCd6, and a divalent compound YbCd6, are found to order antiferromagnetically. We clarified that the structural order-disorder transition has a great influence on the magnetic ordering and transport properties. The Neel temperature of RCd6 (R: Nd, Sm, Tb, and Dy) with the structural order-disorder transition is appreciably higher than the de Gennes scaling normalized by the Neel temperature of GdCd6, while the the Neel temperature of RCd6 (R: Ho, Er, and Tm) without the structural transition approximately follows the de Gennes scaling. Moreover, the electrical resistivity of RCd6 with the structural transition decreases monotonically below the Neel temperature, while it increases below the Neel temperature and a large residual resistivity remains at low temperatures in RCd6 without the structural transition. The contribution of an Einstein oscillator to the phonon specific heat is also discussed in YCd6 and LuCd6.

    DOI: 10.1143/JPSJ.81.024720

    Web of Science

    researchmap

  • Metamagnetic Behavior in Heavy Fermion Compounds UCo2Zn20 and UIr2Zn20 査読

    Y. Hirose, K. Enoki, S. Yoshiuchi, T. Takeuchi, F. Honda, K. Sugiyama, E. Yamamoto, Y. Haga, M. Hagiwara, K. Kindo, R. Settai, Y. Onuki

    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2011)   391   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    The metamagnetic behavior, which is typical in heavy fermion compounds, is observed in UCo2Zn20 and UIr2Zn20 at H-m = 80 and 20 kOe, respectively. Reflecting the metamagnetic behavior, the magnetoresistance is suppressed in magnetic fields larger than H-m, and the corresponding A-value of a Fermi liquid relation in the electrical resistivity sigma = sigma(0) + AT(2) indicates a peak at around H-m. Pressure suppresses this behavior in UIr2Zn20.

    DOI: 10.1088/1742-6596/391/1/012021

    Web of Science

    researchmap

  • Field-Induced Ordering in the Heavy Fermion Compound YbCo2Zn20 査読

    Yasuyuki Shimura, Toshiro Sakakibara, Shingo Yoshiuchi, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2011)   391   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    DC Magnetization of the heavy-fermion compound YbCo2Zn20 was examined at very-low temperatures down to 0.07 K in the field up to 14.5 T. In addition to the nearly-isotropic metamagnetic behavior at 0.6 T, a new metamagnetic behavior is observed in the field variation of magnetization M(H) at 6 T only for H parallel to [111]. For the same field direction, a clear kink appears in the temperature dependence of the magnetization M(T) for fields above 6 T. These results strongly suggest the existence of a new ordered phase induced by magnetic fields. The H - T phase diagram as well as the anisotropy in M(H) above similar to 2 T are best explained by a level crossing of the low-lying crystalline-electric-field states by magnetic fields.

    DOI: 10.1088/1742-6596/391/1/012066

    Web of Science

    researchmap

  • Characteristic magnetic phase diagram in heavy-fermion compound YbCo2Zn20 査読

    T. Takeuchi, S. Yoshiuchi, M. Ohya, M. Matsushita, S. Yasui, Y. Hirose, K. Sugiyama, F. Honda, R. Settai, Y. Onuki

    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2011)   391   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We studied the magnetic field versus temperature phase diagram of the heavy-fermion compound YbCo2Zn20 with the cubic CeCr2Al20-type structure by measuring the specific heat, ac-susceptibility, and electrical resistivity under magnetic fields. In a low magnetic field region, a metamagnetic behavior was observed at H-m = 6 kOe for three principal field directions below T-chi max = 0.32 K, at which the temperature dependence of ac-susceptibility shows a local broad maximum. Two crossover lines were found below and above H-m. At high magnetic fields, the heavy-fermion state was rapidly suppressed with increasing magnetic field, and the field-induced ordered phase appeared in a very limited field direction around H parallel to &lt; 111 &gt; above the transition field H-Q = 60 kOe in the temperature range below T-Q = 0.6 K.

    DOI: 10.1088/1742-6596/391/1/012072

    Web of Science

    researchmap

  • Effect of magnetic field in heavy-fermion compound YbCo2Zn20 査読

    Koji Kaneko, Shingo Yoshiuchi, Tetsuya Takeuchi, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2011)   391   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    Inelastic neutron scattering experiments on poly crystalline sample of heavy-fermion compound YbCo2Zn20 were carried out in order to obtain microscopic insights on the ground state and its magnetic field response. At zero field at 300 mK, inelastic response consists of two features: quasielastic scattering and a sharp peak at 0.6 meV. With increasing temperature,a broad peak comes up around 2.1 meV, whereas quasielastic response gets broader and the peak at 0.6 meV becomes unclear. By applying magnetic field, the quasielastic response exhibits significant broadening above 1 T, and the peak at 0.6 meV is obscure under fields. The peaks in inelastic spectra and its temperature variation can be ascribed to the suggested crystal-field model of Gamma(6) - Gamma(8) - Gamma(7) with the overall splitting of less than 3 meV. The observed quasielastic response and its rapid broadening with magnetic field indicates that the heavy-electron state arises from the ground state doublets, and are strongly suppressed by external field in YbCo2Zn20,

    DOI: 10.1088/1742-6596/391/1/012026

    Web of Science

    researchmap

  • Specific Heat Study of the Non-centrosymmetric Superconductor LaPt3Si in Magnetic Fields 査読

    G. Motoyama, M. Shiotsuki, Y. Oda, A. Yamaguchi, A. Sumiyama, T. Takeuchi, R. Settai, Y. Onuki

    26TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT26), PTS 1-5   400   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We have measured the specific heat of poly- and single-crystalline LaPt3Si samples in various magnetic fields. In zero magnetic field, we observed distinct superconducting transitions at T-c similar to 0.64 K and 0.61 K for the poly- and single crystals, respectively. Temperature T dependences of the specific heat C of both samples around T-c resembled each other and could be well described by an exponential equation for a conventional superconductor at low temperatures. In a magnetic field, a characteristic peak of C/T appeared while the T-c was considerably suppressed. These trends were pronounced for the single crystal. The transition of the polycrystal became broad above 40 Oe and a characteristic tail appeared at temperatures above the peak of C/T. We suggest that the tail is induced by domains that have crystallographic disorders of the non-centrosymmetry and a higher critical magnetic field than that of the bulk. These domains became superconducting at temperatures above the peak of C/T, and then formed the tail. Both the poly- and single-crystalline LaPt3Si samples have been found to show characteristics that are in-between those of type-I and type-II superconductors.

    DOI: 10.1088/1742-6596/400/2/022079

    Web of Science

    researchmap

  • Pressure-induced novel superconductivity and heavy fermion state in rare earth compounds 査読

    Fuminori Honda, Yusuke Hirose, Shingo Yoshiuchi, Shinichi Yasui, Tetsuya Takeuchi, Ismardo Bonalde, Katsuya Shimizu, Rikio Settai, Yoshichika Onuki

    26TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT26), PTS 1-5   400   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We have carried out the electrical resistivity measurements under high pressures up to 24 GPa for CeTX3 (T: Co and Ir, X: Si and Ge), CePd5Al2 and YbIr2Zn20 in order to investigate quantum criticality and superconductivity. Antiferromagnets CeTX3 with the non-centrosymmetric tetragonal structure show superconductivity under high pressures and reveal a huge upper critical field for H parallel to [001]. An antiferromagnet CePd5Al2, which is an isostructural family of a heavy fermion superconductor NpPd5Al2, also shows superconductivity under high pressures. In these compounds, superconductivity appears in the vicinity of quantum critical point. On the other hand, YbIr2Zn20 without magnetic ordering approaches to the quantum critical point with increasing pressure, and exhibits a super-heavy fermion state exceeding 10 J/(K-2 center dot mol).

    DOI: 10.1088/1742-6596/400/2/022028

    Web of Science

    researchmap

  • Electronic states and superconducting properties of non-centrosymmetric rare earth compounds 査読

    Yoshichika Onuki, Rikio Settai

    Lecture Notes in Physics   847   81 - 126   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The property of Fermi surface splitting in the non-centrosymmetric tetragonal compounds RPt 3Si (R: La, Ce) and RT X 3 (T: Co, Rh, Ir
    X: Si, Ge) are studied by de Haas-van Alphen experiments and compared with energy band calculations. Moreover superconducting properties are investigated in these compounds. In particular, in CeIrSi 3 the unusual behavior of the upper critical field H c2 at pressures around 2.6 GPa is analyzed in detail. At 2.6 GPa, a huge value of H c2(0) ≃450 kOe is found for magnetic fields along the [0 0 1] direction of the non-centrosymmetric tetragonal crystal structure, in contrast to the smaller H c2(0) ≃ 95 kOe for H ∥ [1 1 0]. © Springer-Verlag Berlin Heidelberg 2012.

    DOI: 10.1007/978-3-642-24624-1_3

    Scopus

    researchmap

  • Systematic study of the 4f electronic state in RRhIn <inf>5</inf> and RCu <inf>2</inf>Si <inf>2</inf> (R: Rare earth)

    Tetsuya Takeuchi, Tetsuya Takeuchi, Nguyen Van Hieu, Nguyen Duc Dung, Yuji Takeda, Yasunori Nakano, Kiyohiro Sugiyama, Rikio Settai, Yoshichika Onuki, Tatsuma D. Matsuda, Etsuji Yamamoto, Yoshinori Haga

    e-Journal of Surface Science and Nanotechnology   9   446 - 453   2011年12月

     詳細を見る

    記述言語:英語   出版者・発行元:The Surface Science Society of Japan  

    Systematic study of the 4f electronic state in RRhIn 5 and RCu 2Si 2 has been done by using single crystalline samples which were successfully grown by the flux method. Most of RRhIn5 compounds order antiferromagnetically at low temperatures, except when R=Y, La, Pr and Yb. The observed anisotropic features in the magnetic susceptibility and magnetization have been analyzed on the basis of the crystalline electric field (CEF) model. The observed anisotropy in the magnetic susceptibility in the paramagnetic state is well explained by the CEF effect. Specific heat measurements on a series of ternary compound RCu 2Si 2 have been performed by the quasiadiabatic heat pulse method in the temperature range down to 100 mK. We observed the nuclear specific heat at low temperatures and estimated the magnitude of internal effective magnetic field H eff at the nucleus in RCu 2Si 2. © 2011 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2011.446

    Scopus

    CiNii Article

    researchmap

  • Pressure and Temperature Dependences of the Electronic Structure of CeIrSi3 Probed by Resonant X-ray Emission Spectroscopy 査読

    Hitoshi Yamaoka, Ignace Jarrige, Naohito Tsujii, Akio Kotani, Jung-Fu Lin, Fuminori Honda, Rikio Settai, Yoshichika Onuki, Nozumu Hiraoka, Hirofumi Ishii, Ku-Ding Tsuei

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80 ( 12 )   2011年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Pressure and temperature dependences of the electronic structure of the heavy-fermion superconductor CeIrSi3 have been investigated using partial fluorescence yield x-ray absorption spectroscopy and resonant x-ray emission spectroscopy at the Ce L-3 edge. Ce is in a weakly mixed valence state at ambient pressure, mostly f(1) with a small contribution from the f(0) component. Pressure-induced increase of the Ce valence becomes apparent above 4 GPa, concomitantly with the disappearance of the superconductivity. No temperature dependence of the Ce valence is observed within the measured temperature range down to 24 K.

    DOI: 10.1143/JPSJ.80.124701

    Web of Science

    researchmap

  • Electronic structure of YbCu2Ge2 studied by soft x-ray angle-resolved photoemission spectroscopy 査読

    A. Yasui, S. -I. Fujimori, I. Kawasaki, T. Okane, Y. Takeda, Y. Saitoh, H. Yamagami, A. Sekiyama, R. Settai, T. D. Matsuda, Y. Haga, Y. Onuki

    PHYSICAL REVIEW B   84 ( 19 )   2011年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We have measured three-dimensional band structure and Fermi surfaces (FSs) ofYbCu(2)Ge(2), which has recently become recognized as a nearly divalent Yb-based compound, by using soft x-ray angle-resolved photoemission spectroscopy. We clarified that the bands with finite Yb 4f contribution cross the Fermi level and are slightly involved in the formation of the FSs, in line with the valence-fluctuating state of YbCu2Ge2. The obtained valence-band dispersions and the FSs are well explained by a relativistic band-structure calculation based on a local-density-approximation (LDA). These results suggest that the LDA calculation is a good starting point for understanding of the electronic state of YbCu2Ge2 as well as nearly divalent Yb-based compounds.

    DOI: 10.1103/PhysRevB.84.195121

    Web of Science

    researchmap

  • Field-Induced Quadrupolar Ordered Phase for H parallel to &lt; 111 &gt; in Heavy-Fermion Compound YbCo2Zn20 査読

    Tetsuya Takeuchi, Shingo Yoshiuchi, Masahiro Ohya, Yuki Taga, Yusuke Hirose, Kiyohiro Sugiyama, Fuminori Honda, Masayuki Hagiwara, Koichi Kindo, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80 ( 11 )   2011年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Magnetic susceptibility, high-field magnetization up to 500 kOe, and specific heat in a wide temperature range from 0.06 to 300K were measured for single crystals of the cubic heavy-fermion compound YbCo2Zn20 in order to elucidate the electronic states of the compound at low temperatures. A strong increase in the magnetic specific heat in the form of C-mag/T below similar to 1K is approximately explained by the resonant level model for S = 1/2 with the Kondo temperature T-K = 1 K, and an extremely large C-mag/T similar or equal to 8 J/(K-2.mol) below about 0.2K is explained by considering the magnetic entropy of the doublet ground state in the 4f crystalline electric field (CEF) scheme of an Yb3+ ion, which corresponds to an extremely large electronic specific heat coefficient. The field-induced ordered phase for H parallel to &lt; 111 &gt;, which has recently been found by low-temperature magnetization measurements, was precisely studied by electrical resistivity and specific heat measurements, and was observed in a limited angular range around the &lt; 111 &gt; direction. On the basis of CEF analyses, the level crossing of the two lowest CEF states is essentially important to understand the field-induced ordered phase, which can be reduced to a field-induced antiferro-quadrupolar ordering based on the Gamma(3)-type quadrupole moment O-2(0).

    DOI: 10.1143/JPSJ.80.114703

    Web of Science

    researchmap

  • Field-Induced Antiferromagnetic State in Non-centrosymmetric Superconductor CeIrSi3 査読

    Rikio Settai, Keisuke Katayama, Dai Aoki, Ilya Sheikin, Georg Knebel, Jacques Flouquet, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80 ( 9 )   2011年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have carried out the electrical resistivity and ac specific heat measurements under pressure P and magnetic field H in a pressure-induced superconductor CeIrSi3 with the noncentrosymmetric tetragonal crystal structure. Superconductivity is observed in a wide pressure region from 1.9 GPa to about 3.5 GPa. The antiferromagnetic state disappears at P-c = 2.25 GPa under H = 0, but in magnetic field we have found an antiferromagnetic state. The corresponding electrical resistivity in constant magnetic field decreases rather steeply below the Neel temperature T-N under pressures up to about 2.4 GPa, while it shows an upturn anomaly at T-N under pressures larger than 2.4 GPa. The ac specific heat also indicates a clear jump at T-N in magnetic field. When the antiferromagnetic phase exists in magnetic field, the superconducting transition becomes broad, possessing a transition width Delta T-sc = 0.2-0.5 K. On the other hand, it becomes extremely sharp, with Delta T-sc = 0.03K even at 17 T under P = 2.55 GPa, for example, when the antiferromagnetic phase disappears. The upper critical field H-c2 for H parallel to [001] is also extremely enhanced around 2.5-2.7 GPa, and the H-c2(0) value reaches about 45 T at P-c* similar or equal to 2.63 GPa, even though the superconducting transition temperature T-sc = 1.6K is very small. The electronic instability is realized in magnetic field at P-c*. The present characteristic heavy fermion superconductivity in the noncentrosymmetric structure is compared with the similar pressure-induced superconductivity of CeRhIn5.

    DOI: 10.1143/JPSJ.80.094703

    Web of Science

    researchmap

  • High Field Magnetoresistance and de Haas-van Alphen Effect in LaRu2Al10 査読

    Masahito Sakoda, Shuhei Tanaka, Eiichi Matsuoka, Hitoshi Sugawara, Hisatomo Harima, Fuminori Honda, Rikio Settai, Yoshichika Onuki, Tatsuma D. Matsuda, Yoshinori Haga

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80 ( 8 )   2011年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have measured the magnetoresistance and de Haas-van Alphen (dHvA) effect in LaRu2Al10, which is a reference compound of CeRu2Al10 that exhibits an unusual transition at T-0 similar or equal to 27 K. The magnetoresistance increases with increasing magnetic field at low temperatures in the wide field directions, suggesting that LaRu2Al10 is a compensated metal without an open orbit. From the dHvA experiments, about three dHvA frequency branches whose cyclotron effective masses are close to 1m(0) (m(0): rest mass of an electron) were detected. The observed dHvA branches for the main Fermi surface are well explained by the results of band structure calculation based on a full potential linearized augmented-plane-wave (FLAPW) method and local-density approximation (LDA), that demonstrates the multiply connected Fermi surface with no nesting property in LaRu2Al10.

    DOI: 10.1143/JPSJ.80.084716

    Web of Science

    researchmap

  • Pressure-induced structural phase transitions in UIr 査読

    H. Kotegawa, S. Araki, T. Akazawa, A. Hori, Y. Irie, S. Fukushima, H. Hidaka, T. C. Kobayashi, K. Takeda, Y. Ohishi, K. Murata, E. Yamamoto, S. Ikeda, Y. Haga, R. Settai, Y. Onuki

    PHYSICAL REVIEW B   84 ( 5 )   2011年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Strain and resistivity measurements in UIr showed the occurrence of two structural phase transitions under high pressure, indicating the existence of three phases I-III, with slightly different crystal structures. It is suggested that ferromagnetic phases FM1-FM3 emerge in phases I-III, respectively. The pressure-temperature phase diagram was sensitive to the hydrostaticity of pressure. FM3 and superconductivity are observed in the measurements in which Daphne 7373 is used as a pressure-transmitting medium; however they are both absent in the case where petroleum ether is used as a pressure-transmitting medium. These results indicate a close relationship between ferromagnetism and superconductivity.

    DOI: 10.1103/PhysRevB.84.054524

    Web of Science

    researchmap

  • Characteristic Heavy Fermion Properties in YbCu2Si2 and YbT2Zn20 (T: Co, Rh, Ir) 査読

    Yoshichika Onuki, Shinichi Yasui, Masaki Matsushita, Shingo Yoshiuchi, Masahiro Ohya, Yusuke Hirose, Nguyen D. Dung, Fuminori Honda, Tetsuya Takeuchi, Rikio Settai, Kiyohiro Sugiyama, Etsuji Yamamoto, Tatsuma D. Matsuda, Yoshinori Haga, Toshiki Tanaka, Yasunori Kubo, Hisatomo Harima

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We studied the Fermi surface properties of YbCu2Si2 and YbCu2Ge2 with the tetragonal structure by measuring the de Haas-van Alphen (dHvA) oscillations, together with the energy band calculations. It was clarified that 4f electrons contribute to the Fermi surface of a valence fluctuating compound YbCu2Si2, but not to that of a divalent compound YbCu2Ge2. Namely, the Fermi surface of YbCu2Si2 contains the 4f-components considerably and the corresponding cyclotron effective mass m(c)* of the main Fermi surface is large, m(c)*=30-40m(0) (m(0) : rest mass of an electron). We also studied the heavy fermion properties of YbT2Zn20 (T : Co, Rh, Ir) with the cubic caged structure. The metamagnetic behavior or an abrupt nonlinear increase of magnetization was observed at 6 kOe in YbCo2Zn20, 63 kOe in YbRh2Zn20, and 97 kOe in YbIr2Zn20 for H parallel to &lt; 100 &gt;, which was measured at 60 mK in YbCo2Zn20 and 1.3 K in YbRh2Zn20 and YbIr2Zn20. The metamagnetic field is found to be a good parameter to reach the quantum critical point under pressure for YbIr2Zn20. By measuring the electrical resistivity under pressure and magnetic field, we clarified that the electronic state close to the quantum critical point is realized in YbIr2Zn20 at 5.2 GPa and also YbCo2Zn20 at ambient pressure. The corresponding heavy cyclotron effective mass of 100-500m(0) at 0 kOe was estimated from the field dependence of the root A value in the low-temperature electrical resistivity rho = rho(0) + AT(2) under pressure and magnetic field and the cyclotron mass obtained from the dHvA experiment at ambient pressure and high magnetic fields.

    DOI: 10.1143/JPSJS.80SA.SA003

    Web of Science

    researchmap

  • High-Field de Haas-van Alphen Effect in non-centrosymmetric CeCoGe3 and LaCoGe3 査読

    Ilya Sheikin, Pierre Rodiere, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report on de Haas-van Alphen effect measurements in the non-centrosymmetric systems CeCoGe3 and LaCoGe3 in magnetic field up to 28 Testa. In both compounds, two new high frequencies were observed in high fields. The frequencies were not detected in previous lower field measurements. The frequencies do not originate from magnetic breakdown, and, therefore, are likely to be intrinsic features of the compounds. In CeCoGe3, the corresponding effective masses are strongly enhanced, being of the order of 30 bare electron masses.

    DOI: 10.1143/JPSJS.80SA.SA020

    Web of Science

    researchmap

  • Effect of Pressure on the Metamagnetism in YbIr2Zn20 査読

    Fuminori Honda, Shinichi Yasui, Shingo Yoshiuchi, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have measured the electrical resistivity under magnetic field and pressure for YbIr2Zn20 with the cubic caged structure, and created the evolution of an electronic state in the quantum critical region. The new electronic state at about 5.0 GPa corresponds to the heavy ferrmion state with a very small Kondo temperature T-K = 0.1 - 0.2 K from the metamagnetic behavior observed at the magnetic field H-m = 1.5 kOe. The corresponding cyclotron effective mass at 0 kOe is estimated to be about 450 m(0).

    DOI: 10.1143/JPSJS.80SA.SA050

    Web of Science

    researchmap

  • Low-Temperature Magnetization of the Metamagnetic Heavy Fermion Compound YbIr2Zn20 査読

    Yasuyuki Shimura, Toshiro Sakakibara, Shingo Yoshiuchi, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    DC magnetization of YbIr2Zn20 was measured in magnetic fields H (parallel to [100]) up to 14.5 T at low temperatures down to 0.09 K, focusing attention on the metamagnetic behavior. At the base temperature of T = 0.09 K, three sharp structures were observed in the differential susceptibility dM/dH at 6.2, 9.7 and 11.2 T, with the peak at 9.7 T being the largest. The amplitudes of these anomalies are strongly T dependent and those at 6.2 and 11.2 T disappear above 0.7 and 0.4 K, respectively. The peak value of dM/dH of the main peak at 9.7 T exhibits an unusual temperature variation on cooling below 1 K, with a divergent tendency persisting towards the lowest temperature. This feature is different from what one would expect for the normal Fermi liquid systems, and suggests the existence of underlying quantum critical behavior. The results are discussed in relation to the recently proposed field-induced valence crossover scenario.

    DOI: 10.1143/JPSJS.80SA.SA051

    Web of Science

    researchmap

  • Metamagnetic Behaviour in CeCu6 査読

    Yusuke Hirose, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The metamagnetic behaviour, which corresponds to one of the characteristic properties in the heavy fermion compounds, was studied by measuring the electrical resistivity under pressure and magnetic field for a typical heavy fermion compound CeCu6 with orthorhombic structure. The transverse magnetoresistance at 100 mK indicated a peak structure at H-m = 20 kOe for the magnetic field H//c-axis under ambient pressure. H-m is found to increase linearly as a function of pressure and indicates H-m = 102 kOe at 1.75 GPa, for example. The quantum critical point is thus likely to exist at a slightly negative pressure value of similar to 0.21 GPa from extrapolating H-m to zero. The rho(0) and A values in the electrical resistivity rho = rho(0) + AT(2) decrease steeply in magnitude with increasing pressure and magnetic field, indicating that the heavy fermion state is destroyed by pressure and magnetic field.

    DOI: 10.1143/JPSJS.80SA.SA065

    Web of Science

    researchmap

  • Electrical Resistivity of Ce2Ir3Ge5 under High Pressure 査読

    M. Nakashima, T. Kawata, Y. Amako, S. Yoshiuchi, Y. Hirose, K. Matsubayashi, Y. Uwatoko, A. Thamizhavel, F. Honda, R. Settai, Y. Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured electrical resistivity on antiferromagnet Ce2Ir3Ge5 under high pressure up to 8 GPa. It is shown that the Neel temperature (= 9.5 K) at ambient pressure decreased by increased pressure. The Neel temperature seems to be zero at a critical pressure P-c similar or equal to 2.0 GPa suddenly. The variation by higher pressure above 2.0 GPa does not seem prominence up to 8 GPa.

    DOI: 10.1143/JPSJS.80SA.SA066

    Web of Science

    researchmap

  • Specific Heat on the Non-centrosymmetric Superconductor LaPt3Si 査読

    Masahiro Shiotsuki, Gaku Motoyama, Yasukage Oda, Akira Yamaguchi, Akihiko Sumiyama, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have measured specific heat of poly and single crystalline LaPt3Si samples under various magnetic fields. For zero magnetic field, we observed a distinct peak and jump in the specific heat at the super-conducting transition temperature T-c similar to 0.64 K and 0.61 K for the poly and single crystals, respectively. Temperature dependences of the specific heat of both samples below T-c can be well-described by a exponential equation for a conventional superconductor at zero magnetic field. The jump at T-c of single crystal is still distinct under magnetic fields. On the other hand, the peak of the poly crystal becomes broad above 40 Gauss. The broad additional specific heat tail appears at higher temperatures than the T-c expected from the results of the single crystal. We show, for the first time, the temperature dependence of superconducting critical magnetic field H-c(T) obtained from the specific heat measurement. Small anisotropy of H-c(T) was observed for the single crystal, with H-c,(0) = 66 and 61 Gauss for H//a and H//c, respectively.

    DOI: 10.1143/JPSJS.80SA.SA070

    Web of Science

    researchmap

  • Field-induced antiferromagnetic state in a pressure-induced superconductor CeIrSi3 査読

    Rikio Settai, Keisuke Katayama, Dai Aoki, Georg Knebel, Jacques Flouquet, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    CeIrSi3 is an antiferromagnet with a Neel temperature T-N=5.0 K at ambient pressure. With increasing pressure, T-N decreases monotonically and the antiferromagnetic (AF) ordering disappears at pressure P-c=2.25 GPa, and shows pressure-induced superconductivity above 1.9 GPa. We have investigated the superconducting and field-induced AF states in CeIrSi3 by measureing the electrical resistivity and ac-specific heat measurements under pressure and magnetic field. At 2.40 GPa, for example, the AF phase is induced by magnetic field above 6 T. The upper critical field H-c2 is suppressed in the field-induced anti-ferromagneic phase. We discussed the field-induced AF state in CeIrSi3, comparing with that in CeRhIn5, which possesses a similar pressure phase diagram.

    DOI: 10.1143/JPSJS.80SA.SA069

    Web of Science

    researchmap

  • Josephson Effect of Heavy-Fermion Superconductors Measured in a 3-axes Magnetometer 査読

    Akihiko Sumiyama, Naoko Ikeda, Yoshihiro Aoki, Gaku Motoyama, Akira Yamaguchi, Takashi Yasuda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have fabricated a 3-axes magnetometer that can reduce the residual magnetic field below 50 mu G for each direction. Josephson critical current I-c between a noncentrosymmetric superconductor (CePt3Si or LaPt3Si) and Al has been investigated inside it to avoid the magnetic-flux trapping during the superconducting transition and found to show a magnetic field H dependence similar to the previous one obtained using one-axis magnetometer; asymmetric patterns with respect to H = 0 are commonly observed for CePt3Si and LaPt3Si. This suggests that the residual-field components perpendicular to H applied for I-c(H) measurements does not basically affect the I-c(H) patterns.

    DOI: 10.1143/JPSJS.80SA.SA071

    Web of Science

    researchmap

  • Magnetic-field-induced Metallic State in beta-US2 査読

    Kiyohiro Sugiyama, Yusuke Hirose, Kentaro Enoki, Shugo Ikeda, Etsuji Yamamoto, Naoyuki Tateiwa, Yoshinori Haga, Takanori Kida, Masayuki Hagiwara, Koichi Kindo, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    beta-US2 with the orthorhombic structure is an interesting compound of which the electrical property is changed from a metallic state to an insulating state at temperatures lower than 80 K. To clarify the present metal-insulator change, we carried out the magnetization and magnetoresistance measurements in magnetic fields up to 50 T. The magentization at 4.2 K saturates above 40 T, reaching 1.75 mu(B)/U at 50 T for the magnetic field along the magentic easy-axis, namely the [001] direction. The corresponding electrical resistivity at 4.2 K is steeply reduced in magnitude from 1 x 10(3) Omega.cm to 2 x 10(-2) Omega.cm at 50 T only when the magnetic field is applied along the [001] direction. The temperature dependence of the electrical resistivity at 50 T indicates a usual metallic behaviour. The conduction electrons are most likely released from the trapped U-sites when the 5f-CEF magnetic moments are fully polarized in high magnetic field of 50 T. The present experimental results are discussed from the viewpoint of the magnetic polaron.

    DOI: 10.1143/JPSJS.80SA.SA104

    Web of Science

    researchmap

  • Evidence of a Field-Induced Ordering in YbCo2Zn20 in a [111] Magnetic Field 査読

    Yasuyuki Shimura, Toshiro Sakakibara, Shingo Yoshiuchi, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80 ( 7 )   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    DC magnetization (M) measurements were done on a single crystal of YbCo2Zn20 at very low temperatures (T) down to 0.07 K in magnetic fields H parallel to [111]. In addition to the metamagnetic behavior at mu H-0(m) = 0.6 T already known, we found a new metamagnetic transition at mu H-0'(m) = 6 T whose critical field moves to higher fields with increasing T. Moreover, in fields above 6 T, temperature dependence of the magnetization M(T) shows a kink below 0.6 K. These anomalies indicate the presence of a new field-induced ordered phase. In addition, a broad peak is observed in M(T) in fields above 3 T outside the ordered phase. These results are best explained by a level crossing of the low-lying crystalline-electric-field state with the ground state, possibly assisted by a valence change in magnetic fields.

    DOI: 10.1143/JPSJ.80.073707

    Web of Science

    researchmap

  • Fermi Surface Property and Characteristic Crystalline Electric Field Effect in PrIr2Zn20 査読

    Masaki Matsushita, Jyunya Sakaguchi, Yuki Taga, Masahiro Ohya, Shingo Yoshiuchi, Hisashi Ota, Yusuke Hirose, Kentaro Enoki, Fuminori Honda, Kiyohiro Sugiyama, Masayuki Hagiwara, Koichi Kindo, Toshiki Tanaka, Yasunori Kubo, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80 ( 7 )   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the de Haas-van Alphen (dHvA) oscillations, electrical resistivity, magnetic susceptibility, magnetization, and specific heat of PrIr2Zn20, which has recently been suggested as a heavy-fermion superconductor. Several dHvA branches with small frequencies ranging from 0.33 x 10(6) to 8.00 x 10(6) Oe were detected in the dHvA experiment, which were well explained by the results of energy band calculations for LaIr2Zn20 using the lattice parameter of PrIr2Zn20. Moreover, the cyclotron effective mass is small, i.e., less than 1m(0) (m(0): rest mass of an electron). This means that 4f electrons are fully localized and do not contribute to the Fermi surface. Similar dHvA results were obtained for the reference compound LuIr2Zn20. Thus, superconductivity in PrIr2Zn20, which has been observed very recently below 0.05 K, is not due to heavy quasiparticles. In fact, the present superconductivity disappears at a magnetic field of 20 Oe. From the experimental results of magnetic susceptibility, magnetization, and specific heat, we estimated the 4f crystalline electric field (CEF) scheme of PrIr2Zn20: Gamma(3) (0 K)-Gamma(4) (separated from a non-Kramers Gamma(3) doublet by 36.0 K)-Gamma(1) (86.4 K)-Gamma(5) (103 K). On the basis of this CEF scheme, we discuss a broad Schottky peak in the magnetic specific heat at 0.4K and the metamagnetic-like anomaly of magnetization at H-m similar or equal to 50 kOe for H parallel to &lt; 100 &gt;.

    DOI: 10.1143/JPSJ.80.074605

    Web of Science

    researchmap

  • Crossover Phase Diagram in Heavy Fermion Compound YbCO2Zn20 査読

    Tetsuya Takeuchi, Masahiro Ohya, Masaki Matsushita, Shingo Yoshiuchi, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We studied the electronic state and metamagnetic behavior in the heavy fermion compound YbCo2Zn20 by measuring the specific heat, ac-susceptibility, and electrical resistivity under magnetic fields. The magnetic specific heat in the form of C-mag/T increases steeply with decreasing temperature below 10 K and becomes constant with an extremely large value 8 J/(K-2.mol) below about 0.2 K, indicating a Fermi-liquid nature in this temperature range. The magnetic entropy increases rapidly below 10 K and reaches R ln 8 around 60 K, suggesting a small crystalline-electric-field (CEF) splitting energy. From the precise electrical resistivity measurements, together with the C(H)/T and chi(ac) (T) measurements, it was found that there are two crossover lines at low temperatures in the H-T phase diagram for H parallel to &lt; 100 &gt;. The Fermi-liquid state evolves at lower temperatures than these crossover lines.

    DOI: 10.1143/JPSJS.80SA.SA052

    Web of Science

    researchmap

  • Photoemission Study of Rh17S15 Superconductor 査読

    Masaki Fukui, Rikiya Yoshida, Yoshiaki Nakamura, Yukako Kato, Takayuki Muro, Rikio Settai, Yoshichika Onuki, Hisatomo Harima, Masaaki Hirai, Yuji Muraoka, Takayoshi Yokoya

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have investigated the electronic structures of Rh17S15 by using soft x-ray photoemission spectroscopy and first principle band structure calculations. While S 2p core level spectra are explained by symmetric components, Rh 3d core level exhibits asymmetric line shape, suggesting a dominant Rh 4d character at the states near the Fermi level. The binding energy of Rh 4d in Rh17S15 is similar to the one in Rh metal, and this observation implies metallic Rh-Rh bonding. Many features in experimental valence spectra are reasonably described by the calculations, indicating that one particle approximation is a good starting point to understand the electronic properties of Rh17S15. The comparison between the experiment and the calculation suggests that Rh 4d character at the states near the Fermi level is essential for the correlated superconductivity in Rh17S15. However, some deviation between the experiment and the calculation as well as a finite mass enhancement are found, indicating some corrections on the treatment of electron-phonon coupling and/or electron correlations are necessary.

    DOI: 10.1143/JPSJS.80SA.SA111

    Web of Science

    researchmap

  • Origin of High-T-c Inclusion in Noncentrosymmetric Superconductor CePt3Si 査読

    Yoshihiro Aoki, Akihiko Sumiyama, Gaku Motoyama, Akira Yamaguchi, Yasukage Oda, Takashi Yasuda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80 ( 6 )   2011年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    DOI: 10.1143/JPSJ.80.065001

    Web of Science

    researchmap

  • Pressure Evolution of the Magnetic Field induced Ferromagnetic Fluctuation through the Pseudo-Metamagnetism of CeRu2Si2 査読

    Dai Aoki, Carley Paulsen, Tatsuma D. Matsuda, Liam Malone, Georg Knebel, Pierre Haen, Pascal Lejay, Rikio Settai, Yoshichika Onuki, Jacques Flouquet

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   80 ( 5 )   2011年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Resistivity measurements performed under pressure in the paramagnetic ground state of CeRu2Si2 are reported. They demonstrate that the relative change of effective mass through the pseudo metamagnetic transition is invariant under pressure. The results are compared with the first order metamagnetic transition due to the antiferromagnetism of Ce0.9La0.1Ru2Si2 which corresponds to the "negative" pressure of CeRu2Si2 by volume expansion. Finally, we describe the link between the spin-depairing of quasiparticles on CeRu2Si2 and that of Cooper pairs on the unconventional heavy fermion superconductor CeCoIn5.

    DOI: 10.1143/JPSJ.80.053702

    Web of Science

    researchmap

  • Fermi surface properties of YbCu2Si2 査読

    Tatsuma D. Matsuda, Nguyen Duc Dung, Yoshinori Haga, Shugo Ikeda, Etsuji Yamamoto, Tatsuro Ishikura, Toyoaki Endo, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   247 ( 3 )   757 - 759   2010年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    We succeeded in growing high-quality single crystals of a heavy electron compound. YbCu2Si2. The electronic specific beat coefficient gamma is determined to be 150 mJ/K-2.mol, which is consistent with, the A lie; of the electrical resistivity from Kadowaki-Woods relation. We succeeded in observing the de Haas-van Alphen (dHvA) oscillations. The dHvA frequencies and large cyclotron effective masses in YbCu2Si2 are highly different from those in a non-4f reference compound YCu2Si2. From these dHvA results, the heavy electron state of YbCu2Si2 is characterized by the large contribution of 4f-electrons to the topology of the Fermi surface and also to the strong enhancement of effective mass caused by the spin fluctuations. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI: 10.1002/pssb.200983027

    Web of Science

    researchmap

  • Pressure-induced superconductivity in CePd5Al2 and CeRhGe2, new family of heavy fermion superconductors 査読

    Fuminori Honda, Shingo Yoshiuchi, Yusuke Hirose, Taichi Nakamura, Etsuji Yamamoto, Naoyuki Tateiwa, Yoshinori Haga, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   247 ( 3 )   617 - 620   2010年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    Antiferromagnets CePd5Al2 and CeRhGe2 with the quasi-two dimensional electronic state have been found to become superconductive by measuring the electrical resistivity under pressure. In these compounds, the Neel temperature decreases at high pressure and becomes approximately zero at critical pressure P-c = 9 GPa in CePd5Al2 and P-c = 7 GPa in CeRhGe2. Superconductivity was observed around P-c. In CePd5Al2, the upper critical field H-c2 is found to be highly anisotropic among H parallel to [001] and [100], reflecting nearly cylindrical Fermi surfaces along the tetragonal [001] direction. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI: 10.1002/pssb.200983055

    Web of Science

    researchmap

  • Magnetic and Fermi Surface Properties of CePd5Al2 and PrPd5Al2 査読

    Yasunori Nakano, Fuminori Honda, Tetsuya Takeuchi, Kiyohiro Sugiyama, Masayuki Hagiwara, Koichi Kindo, Etsuji Yamamoto, Yoshinori Haga, Rikio Settai, Hiroshi Yamagami, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   79 ( 2 )   2010年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing sin-le crystals of the antiferromagnet CePd5Al2, and the paramagnet PrPd5Al2 with a tetragonal crystal structure by the Bridgman method, and studied the magnetic and surface properties by measuring the electrical resistivity, magnetic susceptibility, magnetization, specific heat, and de Haas-van Alphen (dHvA) oscillation. We constructed the crystalline electric field (CEF) scheme from the experimentally observed anisotropic magnetic Susceptibility and magnetization Of CePd5Al2 and PrPd5Al2. In both compounds, the B-2(0) Value in the CEF parameters is negative and large, implying that the magnetic easy axis is the [001] direction. The present magnetism of CePd5Al2 and PrPd5Al2 is highly different from that of the heavy fermion superconductor NpPd5Al2 with the magnetic easy axis of the [100] direction. From the dHvA experiment for CePd5Al2 and PrPd5Al2, we observed a few dHvA branches. which correspond to nearly cylindrical band-32 hole and band-33 electron Fermi surfaces Of the non-4f reference LaPd5Al2, Reflecting the anisotropy of effective masses based on the nearly cylindrical Fermi surfaces along the tetragonal [001] direction, the Upper critical field H-c2 for H parallel to [100] in the pressure-induced superconductor CePd5Al2], is larger than that for H parallel to [001]: -dH(c2)/dT = 100kOe/K for H parallel to [100], and -dH(c2)/dT = 18kOe/K for H parallel to [001] at the superconducting transition temperature T-sc = 0.9 K. This anisotropy in H-c2 is also highly different from that of NpPd5Al2, suggesting that superconductivity is closely correlated with magnetism.

    DOI: 10.1143/JPSJ.79.024702

    Web of Science

    researchmap

  • Evolution of the Fermi Surface of BaFe2(As1-xPx)(2) on Entering the Superconducting Dome 査読

    H. Shishido, A. F. Bangura, A. I. Coldea, S. Tonegawa, K. Hashimoto, S. Kasahara, P. M. C. Rourke, H. Ikeda, T. Terashima, R. Settai, Y. Onuki, D. Vignolles, C. Proust, B. Vignolle, A. McCollam, Y. Matsuda, T. Shibauchi, A. Carrington

    PHYSICAL REVIEW LETTERS   104 ( 5 )   2010年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Using the de Haas-van Alphen effect we have measured the evolution of the Fermi surface of BaFe2(As1-xPx)(2) as a function of isoelectric substitution (As/P) for 0.41 &lt; x &lt; 1 (T-c up to 25 K). We find that the volumes of electron and hole Fermi surfaces shrink linearly with decreasing x. This shrinking is accompanied by a strong increase in the quasiparticle effective mass as x is tuned toward the maximum Tc. These results are not explained by simple band structure calculations, and it is likely that these trends originate from the same many-body interactions which give rise to superconductivity.

    DOI: 10.1103/PhysRevLett.104.057008

    Web of Science

    researchmap

  • Sign Reversal of Field-Angle Resolved Heat Capacity Oscillations in a Heavy Fermion Superconductor CeCoIn5 and dx2-y2 Pairing Symmetry 査読

    K. An, T. Sakakibara, R. Settai, Y. Onuki, M. Hiragi, M. Ichioka, K. Machida

    PHYSICAL REVIEW LETTERS   104 ( 3 )   2010年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    To identify the superconducting gap symmetry in CeCoIn5 (T-c = 2.3 K), we measured the angle-resolved specific heat (C-phi) in a field rotated around the c axis down to a very low temperature, 0.05T(c), and made detailed theoretical calculations. In a field of 1 T, a sign reversal of the fourfold angular oscillation in C-phi was observed at T similar or equal to 0.1T(c) upon entering a quasiclassical regime where the maximum of C-phi corresponds to the antinodal direction, coinciding with the angle-resolved density of states (ADOS) calculation. The C-phi behavior, which exhibits minima along the [110] directions, unambiguously allows us to conclude d(x2-y2) symmetry of this system. The ADOS-quasiclassical region is confined to a narrow T and H domain within T/T-c similar to 0.1 and 1.5 T (0.13H(c2)).

    DOI: 10.1103/PhysRevLett.104.037002

    Web of Science

    researchmap

  • Spin Susceptibility of Noncentrosymmetric Heavy-Fermion Superconductor CeIrSi3 under Pressure: Si-29 Knight-Shift Study on Single Crystal 査読

    H. Mukuda, T. Ohara, M. Yashima, Y. Kitaoka, R. Settai, Y. Onuki, K. M. Itoh, E. E. Haller

    PHYSICAL REVIEW LETTERS   104 ( 1 )   2010年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report Si-29 NMR study on a single crystal of the heavy-fermion superconductor CeIrSi3 without an inversion symmetry along the c axis. The Si-29 Knight-shift measurements under pressure have revealed that the spin susceptibility for the ab plane decreases slightly below T-c, whereas along the c axis it does not change at all. The result can be accounted for by the spin susceptibility in the superconducting state being dominated by the strong antisymmetric (Rashba-type) spin-orbit interaction that originates from the absence of an inversion center along the c axis and it being much larger than superconducting condensation energy. This is the first observation which exhibits an anisotropy of the spin susceptibility below T-c in the noncentrosymmetric superconductor dominated by strong Rashba-type spin-orbit interaction.

    DOI: 10.1103/PhysRevLett.104.017002

    Web of Science

    researchmap

  • Pd-105 NQR Study on NpPd5Al2 and CePd5Al2 査読

    H. Chudo, H. Sakai, Y. Tokunaga, S. Kambe, D. Aoki, Y. Haga, T. D. Matsuda, Y. Homma, Y. Nakano, F. Honda, R. Settai, Y. Onuki, H. Yasuoka

    INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)   200   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We report the results of Pd-105 NQR experiments on NpPd5Al2 and CePd5Al2. In the normal state at 6 K, the Pd-105 NQR spectrum consists of four lines in both systems. These lines can be assigned to two sets of +/- 1/ 2 &lt;-&gt; +/- 3/2 and +/- 3/2 &lt;-&gt; +/- 5/2 NQR transitions arising from two crystallographically inequivalent Pd sites. From the analysis of the Pd-105 NQR spectrum the nuclear quadrupole frequency nu(Q), asymmetry parameter eta and electric field gradient V-zz have been deduced.

    DOI: 10.1088/1742-6596/200/1/012020

    Web of Science

    researchmap

  • 5f-electronic states of neptunium compounds: NpGe3, NpRhGa5 and NpCd11 査読

    Y. Onuki, D. Aoki, Y. Homma, Y. Haga, S. Yoshiuchi, R. Settai, H. Sakai, S. Ikeda, E. Yamamoto, A. Nakamura, Y. Shiokawa, T. Takeuchi, H. Yamagami

    ACTINIDES 2009   9   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We studied the electronic states of three typical neptunium compounds, NpGe3, NpRhGa5 and NpCd11. Among them, NpGe3 and NpCd11 with the cubic crystal structure are paramagnets without magnetic ordering, while NpRhGa5 with the tetragonal structure is an antiferromagnet. At high temperatures, the 5f electrons in NpGe3 are almost localized, and the magnetic susceptibility chi(T) approximately follows the Curie-Weiss law. With decreasing temperature, chi(T) shows a broad peak around 50 K, indicating a moderate heavy fermion state at lower temperatures. In fact, the results of the de Haas-van Alphen (dHvA) experiments for NpGe3 are well explained by the 5f-itinerant band model; namely, the 5f electrons contribute to the Fermi surface and the cyclotron effective mass. The cyclotron mass is thus enhanced, ranging from 2.6 to 16 times the rest mass of the electron m(0). In the antiferromagnet NpRhGa5, it was clarified from the results of dHvA experiments and energy band calculations that the 5f electrons contribute to the Fermi surface. The cyclotron mass varies from 8.1 to 11.7 m(0), and the magnetic moment is 0.89 mu(B)/Np. In NpCd11, the 5f electrons are localized in the whole temperature range and do not contribute to the Fermi surface. The corresponding cyclotron mass is thus light, below 1 m(0), revealing no hybridization between the localized 5f electrons and the conduction electrons. The Fermi surface consists of small closed Fermi surfaces, reflecting the small Brillouin zone associated to the large unit cell of the crystal structure in NpCd11. The long Np-Np nearest-neighbor distance (6.568 angstrom) results in the well localized 5f(4) states. Magnetic susceptibility and magnetization curves are well explained in a crystalline electric field (CEF) scheme assuming a singlet ground state and an excited triplet state separated by a 120 K energy gap.

    DOI: 10.1088/1757-899X/9/1/012089

    Web of Science

    researchmap

  • Muon Knight shift measurements in CeCoIn5 below 17 kOe 査読

    W. Higemoto, A. Koda, R. Kadono, K. Ohishi, Y. Haga, H. Shishido, R. Settai, Y. Onuki

    ADVANCED SCIENCE RESEARCH SYMPOSIUM 2009: POSITRON, MUON AND OTHER EXOTIC PARTICLE BEAMS FOR MATERIALS AND ATOMIC/MOLECULAR SCIENCES   225   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    We report muon Knight shift measurements in single crystals of CeCoIn5 below 17 kOe. The muon Knight shift decreases with decreasing temperature below T-c and the reduction of the Knight shift is roughly explained by the Fermi liquid relation. The magnetic field dependence of the reduction of the muon Knight shift is not in proportion to root H. This fact is inconsistent with simple expectation for a d-wave superconductor.

    DOI: 10.1088/1742-6596/225/1/012013

    Web of Science

    researchmap

  • Novel Superconductivity in CeIr(In(1-x)Cd(x))(5) Studied by In-NQR Measurements 査読

    M. Yashima, S. Taniguchi, N. Tagami, H. Mukuda, Y. Kitaoka, Y. Ota, H. Shishido, R. Settai, Y. Onuki

    INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)   200   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We report the superconducting characters in CeIrIn(5) studied by In-NQR measurements under pressure (P). In CeCoIn(5) and CeRhIn(5), the occurrence of superconductivity (SC) is related with the antiferrmagnetic spin fluctuations (AFM-SFs) originating from the antiferromagntic quantum-critical point (AFM-QCP). The high-T(c) SC (T(cmax) &gt; 2 K) is realized in both compounds. However, in CeIrIn5 which is apart from the AFM-QCP, SC occurs even without AFM-SFs and the quite small value of T(cmax) (similar to 1 K) is observed around P = 3 GPa. The mechanism of SC in CeIrIn(5) may be different from that in CeCoIn(5) and CeRhIn(5).

    DOI: 10.1088/1742-6596/200/1/012087

    Web of Science

    researchmap

  • Pressure-Temperature Phase Diagram in Ce(2)RhIn(8) Studied by In-NQR Measurements 査読

    M. Yashima, S. Taniguchi, H. Miyazaki, H. Mukuda, Y. Kitaoka, H. Shishido, R. Settai, Y. Onuki

    INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)   200   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We present a phase diagram for the antiferromagnetism and superconductivity in Ce(2)RhIn(8) probed by In-NQR studies under pressure (P). The quasi-2D character of antiferromagnetic spin fluctuations in the paramagnetic state at P = 0 evolves into a 3D character because of the suppression of antiferromagnetic order for P &gt; P(QCP) similar to 1.36 GPa (QCP: antiferromagnetic quantum critical point). Nuclear-spin-lattice-relaxation rate 1/T(1) measurements revealed that the superconducting order occurs in the P range 1.36 - 1.84 GPa, with maximum T(c) similar to 0.9 K (P(QCP) similar to 1.36 GPa).

    DOI: 10.1088/1742-6596/200/1/012238

    Web of Science

    researchmap

  • Pressure-induced superconductors on heavy fermion system 査読

    Rikio Settai

    Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu   20 ( 2 )   124 - 132   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Since the discovery of a heavy fermion superconductor CeCu2Si2 in 1979, heavy fermion superconductivity has been observed in several rare earth and actinide compounds. Especially the development of high pressure technique and crystal growth makes it possible to investigate the pressure-induced superconductivity in the heavy fermion compounds, possessing magnetic ordering at ambient pressure. In this article, we present recent advances in pressure-induced superconductivity around antiferromagnetic fluctuation, focusing on CeRhIn5 and CeIrSi3.

    DOI: 10.4131/jshpreview.20.124

    Scopus

    researchmap

  • Magnetic Properties of RCoGe3 (R: Ce, Pr, and Nd) and Strong Anisotropy of the Upper Critical Field in Non-centrosymmetric Compound CeCoGe3 査読

    Marie-aude Measson, Hiroshi Muranaka, Tomoya Kawai, Yuuki Ota, Kiyohiro Sugiyama, Masayuki Hagiwara, Koichi Kindo, Tetsuya Takeuchi, Katsuya Shimizu, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   78 ( 12 )   2009年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We grew single crystals of RCoGe3 (R: La, Cc, Pr, and Nd) by the Bi-flux method, and studied the magnetic properties of PrCoGe3 and NdCoGe3 and the pressure-induced superconducting property of CeCoGe3. These compounds crystallize in a non-centrosymmetric tetragonal structure. PrCoGe3 and NdCoGe3 were found to be a paramagnet and an anti ferromagnet with the Neel temperature T-N = 3.8 K, respectively. Crystalline electric field (CEF) schemes were proposed for PrCoGe3 and NdCoGe3. The magnetic property of a pressure-induced superconductor CeCoGe3 is highly different from those of PrCoGe3 and NdCoGe3, or a similar pressure-induced superconductor CeIrSi3. This was discussed in connection with the superconductivity of CeCoGe3. We clarified the upper critical field H-c2 for H parallel to [001] and [100] by measuring the electrical resistivity under pressure P in magnetic fields: H-c2(0) similar or equal to 24T for H parallel to [001] and H-c2(0) similar or equal to 3.1 T for H parallel to [100] at 0 K at P = 7.1 GPa. A huge H-c2(0) value for H parallel to [001] is a combined phenomenon between the Rashba-type antisymmetric spin-orbit interaction and the electronic instability, as observed in CeIrSi3.

    DOI: 10.1143/JPSJ.78.124713

    Web of Science

    researchmap

  • Heavy Fermion State in YbIr2Zn20 査読

    Shingo Yoshiuchi, Masatoshi Toda, Masaki Matsushita, Shinichi Yasui, Yusuke Hirose, Masahiro Ohya, Keisuke Katayama, Fuminori Honda, Kiyohiro Sugiyama, Masayuki Hagiwara, Koichi Kindo, Tetsuya Takeuchi, Etsuji Yamamoto, Yoshinori Haga, Rikio Settai, Toshiki Tanaka, Yasunori Kubo, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   78 ( 12 )   2009年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the high-field magnetization and de Haas-van Alphen (dHvA) oscillations for YbIr2Zn20 with a cubic crystal structure, together with the electrical resistivity and magnetic susceptibility. The magnetic Susceptibility chi with an effective magnetic moment of Yb3+ becomes temperature-independent at low temperatures, with a broad peak at T-chi max = 7.4 K for H parallel to &lt; 110 &gt;. The corresponding magnetization indicates a metamagnetic transition at H-m = 120kOe, consistent with a T-chi max vs H-m relation in the Ce- and U-based heavy fermion Compounds. The large cyclotron masses of 4-27 m(0) are detected in the dHvA experiment, and are found to be reduced at magnetic fields higher than H-m = 120 kOe. The resistivity follows the Fermi liquid relation rho = rho(0) +AT(2) under magnetic field, and the root A value is also found to have a maximum at H-m as a function of magnetic field. From the present experimental results, together with the results of 4f-itinerant energy band calculations, the 4f electrons are found to contribute to the heavy fermion state in YbIr2Zn20.

    DOI: 10.1143/JPSJ.78.123711

    Web of Science

    researchmap

  • Phase diagram for antiferromagnetism and superconductivity in the pressure-induced heavy-fermion superconductor Ce2 RhIn8 probed by i 115 n-NQR 査読

    M. Yashima, S. Taniguchi, H. Miyazaki, H. Mukuda, Y. Kitaoka, H. Shishido, R. Settai, Y. Önuki

    Physical Review B - Condensed Matter and Materials Physics   80 ( 18 )   2009年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We present a phase diagram for the antiferromagnetism and superconductivity in Ce2 RhIn8 probed by In-NQR studies under pressure (P). The quasi-two-dimensional character of antiferromagnetic spin fluctuations in the paramagnetic state at P=0 evolves into a three-dimensional character because of the suppression of antiferromagnetic order for P&gt
    PQCP ∼1.36GPa (QCP: quantum critical point). Nuclear-spin-lattice relaxation rate 1/ T1 measurements revealed that the superconducting order occurs in the P range 1.36-1.84 GPa, with maximum Tc ∼0.9K around PQCP ∼1.36GPa. © 2009 The American Physical Society.

    DOI: 10.1103/PhysRevB.80.184503

    Scopus

    researchmap

  • Phase diagram for antiferromagnetism and superconductivity in the pressure-induced heavy-fermion superconductor Ce2RhIn8 probed by In-115-NQR 査読

    M. Yashima, S. Taniguchi, H. Miyazaki, H. Mukuda, Y. Kitaoka, H. Shishido, R. Settai, Y. Onuki

    PHYSICAL REVIEW B   80 ( 18 )   2009年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We present a phase diagram for the antiferromagnetism and superconductivity in Ce2RhIn8 probed by In-NQR studies under pressure (P). The quasi-two-dimensional character of antiferromagnetic spin fluctuations in the paramagnetic state at P=0 evolves into a three-dimensional character because of the suppression of antiferromagnetic order for P&gt;P-QCP similar to 1.36 GPa (QCP: quantum critical point). Nuclear-spin-lattice relaxation rate 1/T-1 measurements revealed that the superconducting order occurs in the P range 1.36-1.84 GPa, with maximum T-c similar to 0.9 K around P-QCP similar to 1.36 GPa.

    DOI: 10.1103/PhysRevB.80.184503

    Web of Science

    researchmap

  • Magnetic Penetration Depth and Gap Symmetry of the Noncentrosymmetric Superconductors CePt3Si and LaPt3Si 査読

    Rebeca L. Ribeiro, Ismardo Bonalde, Yoshinori Haga, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   78 ( 11 )   2009年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    DOI: 10.1143/JPSJ.78.115002

    Web of Science

    researchmap

  • Unconventional superconductivity of NpPd5Al2 査読

    D. Aoki, Y. Haga, T. D. Matsuda, S. Ikeda, Y. Homma, H. Sakai, Y. Shiokawa, E. Yamamoto, A. Nakamura, R. Settai, Y. Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   21 ( 16 )   2009年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    The high quality single crystals of NpPd5Al2 with the body-centered tetragonal structure were grown by the Pb flux method. NpPd5Al2 was found to be the first Np-based heavy fermion superconductor with the relatively high critical temperature T-sc = 4.9 K. The upper critical field H-c2 is large and highly anisotropic. Corresponding to the heavy electronic state, the initial slope of H-c2 is large, but H-c2 at low temperatures is suppressed by the magnetic field, indicating a strong Pauli paramagnetic effect and the first-order transition at H-c2. These results imply that NpPd5Al2 is located at the proximity of the antiferromagnetic ordering, which might be hidden by the superconductivity. The d-wave superconductivity with a spin singlet state is most likely realized in NpPd5Al2.

    DOI: 10.1088/0953-8984/21/16/164203

    Web of Science

    researchmap

  • Point-contact spectroscopy of the heavy-fermion superconductor CePt3Si 査読

    R. Onuki, A. Sumiyama, Y. Oda, T. Yasuda, R. Settai, Y. Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   21 ( 7 )   2009年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Differential resistance spectra (dV/dI-V characteristics) have been measured for point contacts between the heavy-fermion superconductor (HFS) CePt3Si and a normal metal. Some contacts show a peak at V = 0 that is characteristic of HFS coexisting with a magnetic order such as UPd2Al3, UNi2Al3 and URu2Si2. The evolution of the peak occurs well above the antiferromagnetic transition temperature T-N similar to 2.2 K, so that the direct relationship with the magnetic transition is questionable. The half-width of the peak seems to reflect the crystal field splitting or the spin-wave gap as observed for the above-mentioned HFSs, possibly suggesting that some common scattering process induces the zero-bias peaks in these materials.

    DOI: 10.1088/0953-8984/21/7/075703

    Web of Science

    researchmap

  • Fermi surface of the Pr-based filled skutterudite compound PrOs4P12 査読

    H. Sugawara, Y. Iwahashi, K. Magishi, T. Saito, K. Koyama, H. Harima, D. Kikuchi, H. Sato, T. Endo, R. Settai, Y. Onuki

    PHYSICAL REVIEW B   79 ( 3 )   2009年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We have investigated the Fermi-surface (FS) properties in the Pr-based filled skutterudite PrOs4P12 and its reference compound LaOs4P12 by means of de Haas-van Alphen experiments and the band-structure calculations. The topology of FS in PrOs4P12 is close to that in the reference compound LaOs4P12, indicating a localized nature of 4f electrons in PrOs4P12. Whereas the localized nature of 4f electrons, we have confirmed a highly enhanced cyclotron effective mass of up to 18m(0) in PrOs4P12, which is enhanced about 3.8 times compared to that in LaOs4P12. No nesting property with q=(1,0,0) in the FS of PrOs4P12 has been confirmed in contrast to good nesting properties in PrFe4P12 and PrRu4P12 which exhibit unusual ordered states at low temperatures. A role of both the 4f electron's contributions and the FS nesting property for unusual phase transitions are discussed.

    DOI: 10.1103/PhysRevB.79.035104

    Web of Science

    researchmap

  • Multiband Superconductivity in Heavy Fermion Compound CePt3Si without Inversion Symmetry: An NMR Study on a High-Quality Single Crystal 査読

    Hidekazu Mukuda, Sachihiro Nishide, Atsushi Harada, Kaori Iwasaki, Mamoru Yogi, Mitsuharu Yashima, Yoshio Kitaoka, Masahiko Tsujino, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki, Ernst Bauer, Kohei M. Itoh, Eugene E. Haller

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   78 ( 1 )   2009年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report on novel superconducting characteristics of the heavy fermion (HF) superconductor CePt3Si without inversion symmetry through Pt-195-NMR study on a single crystal with T-c = 0.46 K that is lower than T-c similar to 0.75 K for polycrystals. We show that the intrinsic superconducting characteristics inherent to CePt3Si can be understood in terms of the unconventional strong-coupling state with a line-node gap below T-c = 0.46 K. The mystery about the sample dependence oh T-c is explained by the fact that more or less polycrystals and single crystals inevitably contain some disordered domains, which exhibit a conventional BCS s-wave superconductivity (SC) below 0.8 K. In contrast, the Neel temperature T-N similar to 2.2 K is present regardless of the quality of samples, revealing that the Fermi surface responsible for SC differ from that for the antiferromagnetic order. These unusual characteristics of CePt3Si can be also described by a multiband model; in the homogeneous domains, the coherent HF bands are responsible for the unconventional SC, whereas in the disordered domains the conduction bands existing commonly in LaPt3Si may be responsible for the conventional s-wave SC. We remark that some impurity scatterings in the disordered domains break up the 4f-electrons-derived coherent bands but not others. In this context, the small peak in 1/T-1 just below T-c reported before [Yogi et al. (2004)] is not due to a two-component order parameter composed of spin-ringlet and spin-triplet Cooper pairing states, but due to the contamination of the disorder domains which are in the s-wave SC state.

    DOI: 10.1143/JPSJ.78.014705

    Web of Science

    researchmap

  • Fermi surface of the Pr-based filled skutterudite compound PrOs4P12 査読

    H. Sugawara, Y. Iwahashi, K. Magishi, T. Saito, K. Koyama, H. Harima, D. Kikuchi, H. Sato, T. Endo, R. Settai, Y. Onuki

    Phys. Rev.   79 ( 3 )   1 - 35104   2009年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1103/PhysRevB.79.035104

    J-GLOBAL

    researchmap

  • Multiband Superconductivity in CePt3Si without Inversion Symmetry: Pt-195-NMR Study 査読

    H. Mukuda, S. Nishide, A. Harada, M. Yashima, Y. Kitaoka, M. Tsujino, T. Takeuchi, E. Bauer, R. Settai, Y. Onuki

    25TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT25), PART 5   150   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We report on novel superconducting characteristics of the heavy fermion (HF) superconductor CePt3Si without inversion symmetry through 195 Pt-NMR study on a high quality single crystal with T-c = 0.46 K that is lower than T-c similar to 0.75 K for polycrystals. The observation of short and long components in a nuclear relaxation time T-1 has revealed the presence of inhomogeneities of superconducting characteristics even in a single crystal. By discriminating the clean domain from the disordered domains, we show that the intrinsic superconducting characteristics inherent to CePt3Si can be understood in terms of the unconventional strong-coupling state with a line-node gap below T-c = 0.46 K. Furthermore, it was found that in some disordered domains that are inevitably contained in regardless of polycrystals or single crystals a conventional BCS s-wave superconducting state is realized below T-c similar to 0.75 K. We propose that these unusual superconducting and magnetic characteristics of CePt3Si can be described by a multiband model on the basis of the experimental facts.

    DOI: 10.1088/1742-6596/150/5/052175

    Web of Science

    researchmap

  • Local magnetization study of the first-order superconducting transition in CeCoIn5 査読

    R. Okazaki, H. Shishido, T. Shibauchi, M. Konczykowski, R. Settai, Y. Onuki, Y. Matsuda

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   69 ( 12 )   3208 - 3210   2008年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We report local magnetization measurements on the heavy fermion superconductor CeColn(5) using a inicro-Hall probe. Below a critical point T-0 (similar to 0.8 K), the local magnetization shows a clear jump at the Superconducting transition temperatures for both Hila and HIle, indicating that the phase transition at the upper critical field H-c2 becomes a first-order phase transition. In addition. we observed an undershoot behavior of magnetization jump above mu H-0 similar to 4.75 T (H parallel to c), which suggests a rapid change of textured superconducting structure with vortices and the nodal planes expected in the Fulde-Ferrell-Larkin-Ovchinnikov state. (C) 2008 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jpcs.2008.06.054

    Web of Science

    researchmap

  • Point-contact study of the heavy-fermion superconductor CeCoIn5 査読

    A. Sumiyama, R. Onuki, Y. Oda, H. Shishido, R. Settai, Y. Onuki

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   69 ( 12 )   3018 - 3021   2008年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We have investigated the differential conductance spectra of the point contacts between the heavy-fermion superconductor CeCoIn5 and Pt. Many of them show a double-maximum structure that indicates the superconducting energy gap (sic). The (sic) values derived using Blonder-Tinkham-Klapwijk model, however, varies from 0.47 to 0.77 meV, and yet they are within the scatter of the reported values. The evolution of (sic) below T-c is slow as compared with that of BCS gap probably reflecting the unconventional superconductivity in CeCoIn5. (c) 2008 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jpcs.2008.06.036

    Web of Science

    researchmap

  • Heat capacity of CeIrSi3 under pressure 査読

    Fumiaki Tomioka, Masato Hedo, Izuru Umehara, Yoshiya Uwatoko, Yoshihiko Takano, Yusuke Okuda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   69 ( 12 )   3199 - 3201   2008年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We measured the heat capacity of CelrSi(3)(100 mK&lt;T&lt;6K) under high pressure up to P = 1.38 GPa. The measurements have been used a quasiadiabatic method utilizing a CuBe piston-cylinder pressure cell in a dilution refrigerator. At 0 GPa, a sharp anomaly which indicates the antiferromagnetically transition is observed at T-N = 5 K. T-N decreases monotonically with increasing pressure up to P = 1.38 GPa. The magnetic entropy is released below T-N only 19% of Rln2 at 0GPa. And the magnetic entropy decreases with increasing pressure up to 1.38 GPa, 64% compared to that at 0GPa. (C) 2008 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jpcs.2008.06.033

    Web of Science

    researchmap

  • Electrical and Magnetic Properties of R3Al11 (R = La, Ce, Pr, and Nd) 査読

    Chandrashekhar S. Garde, Tetsuya Takeuchi, Yasunori Nakano, Yuji Takeda, Yuki Ota, Yuichiro Miyauchi, Kiyohiro Sugiyama, Masayuki Hagiwara, Koichi Kindo, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 12 )   2008年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    High-quality single crystals of R3Al11 (R = La, Ce, Pr, and Nd) with the La3Al11-type orthorhombic crystal structure (space group Immm) have been grown by the Al-flux method. For Ce3Al(11), signatures for ferromagnetic and anti ferromagnetic orderings at T-C = 6.3 K and T-N = 3.2 K, respectively, have been observed in the magnetic susceptibility, magnetization, specific heat, and electrical resistivity. An anti ferromagnet Pr3Al11, on the other hand, exhibits two magnetic transitions at T-N1 = 12.6 K and T-N2 = 3.1 K. An antiferromagnet Nd3Al11 also exhibits multiple magnetic transitions at T-N1 = 13.2 K, T-N2 = 9.4 K, T-N3 = 2.9 K, and T-N4 = 1.77 K in zero magnetic field. The transition at T-N4 has a first-order character. The crystalline electric field (CEF) analysis of magnetic susceptibility, magnetization and specific heat data shows that the CEF splitting is larger for Ce3Al11 than for Pr3Al11 and Nd3Al11. The CEF ground state of Pr3Al11 is a singlet. Magnetic order occurs in this compound owing to the exchange mixing of the CEF around state and low-lying excited states. The ferromagnetic like component of the magnetization for H parallel to [010] is characteristic of R3Al11 (R = Ce, Pr, and Nd), which is most likely due to the Dzialoshinsky-Moriya interaction for two nonequivalent R atoms.

    DOI: 10.1143/JPSJ.77.124704

    Web of Science

    researchmap

  • Non-Fermi liquid behavior in the magnetotransport of quasi two-dimensional heavy Fermion compounds CeMIn5 査読

    Y. Nakajima, T. Shibauchi, H. Shishido, H. Nakai, K. Behnia, K. Izawa, M. Hedo, Y. Uwatoko, T. Matsumoto, R. Settai, Y. Onuki, H. Kontani, Y. Matsuda

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   69 ( 12 )   3261 - 3264   2008年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We observe several non-Fermi liquid behaviors in the normal-state transport properties of CeMIn5 (M: Rh and Co) under pressure at low temperatures: (1) The dc-resistivity shows T-linear dependence, p (x T. (2) The magnitude of Hall coefficient vertical bar R-H vertical bar increases rapidly with decreasing temperature, and reaches a value much larger than vertical bar 1/ne vertical bar at low temperatures. (3) The magnetoresistance displays T- and H-dependence that strongly violate Kohler&apos;s rule, and is well scaled by the tangent of the Hall angle, Delta rho(xx)rho(xx) alpha tan(2) Theta(H.) These non-Fermi liquid properties in the electron transport are remarkably pronounced when the AF fluctuations are enhanced in the vicinity of the quantum critical point. Since all of these salient features have been also reported for high-T-c cuprates, we infer that the non-Fermi liquid transport properties capture universal features of strongly correlated electron systems in the presence of strong anti ferromagnetic fluctuations. (C) 2008 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jpcs.2008.06.064

    Web of Science

    researchmap

  • de Haas-van Alphen Effect in LaFePO with Two-Dimensional Cylindrical Fermi Surfaces 査読

    Hitoshi Sugawara, Rikio Settai, Yusuke Doi, Hiroshi Muranaka, Keisuke Katayama, Hiroshi Yamagami, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 11 )   2008年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have Succeeded in observing the de Haas-van Alphen (dHvA) effect in LaFePO. the first reported iron-based superconductor in the iron-oxypnictide family. The four detected dHvA frequencies, which correspond to the cross-sectional areas of Fermi surfaces, approximately follow the 1/cos theta dependence,, where theta is the field-tilted angle from the [001] direction to the [100] and [110] directions in the tetragonal structure. This indicates that all the Fermi surfaces are nearly cylindrical, with the two-dimensional electronic state. The cyclotron effective mass, which was determined from the temperature dependence of the dHvA amplitude, is relatively large, ranging from 1.82 to 2.34m(0). The result of energy band structure calculation revealed that the conduction bands mainly consist of 3d electrons of Fe atoms.

    DOI: 10.1143/JPSJ.77.113711

    Web of Science

    researchmap

  • Anomalous Electronic Behaviors in Ferromagnetic Kondo Lattice SmFe4P12 査読

    Daisuke Kikuchi, Hitoshi Sugawara, Kenya Tanaka, Hidekazu Aoki, Miki Kobayashi, Shotaro Sanada, Keitaro Kuwahara, Yuji Aoki, Hiroaki Shishido, Rikio Settai, Yoshichika Onuki, Hisatomo Harima, Hideyuki Sato

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 11 )   2008年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The electronic properties in SmFe4P12 have been investigated by means of the de Haas-van Alphen effect, transverse magnetoresistance, Hall effect, and band structure calculation. We have found a markedly large anisotropy in the cyclotron effective mass of the 47th band Fermi surface despite its nearly spherical shape. Moreover, this mass enhancement in SmFe4P12 is robust against magnetic field. The transverse magnetoresistance increases nearly quadratically with magnetic field for all field directions; this is unexpected for an ordinary uncompensated metal. The Hall coefficient is found to be 4-fold enhanced at low temperature compared with that at room temperature. These anomalies in transport properties are ascribed to the stronger enhancement of the cyclotron effective mass of the 48th band Fermi Surface.

    DOI: 10.1143/JPSJ.77.114705

    Web of Science

    researchmap

  • Calorimetric Study in Single Crystalline RCu2Si2 (R: Rare Earth) 査読

    Yuji Takeda, Nguyen Duc Dung, Yasunori Nakano, Tatsurou Ishikura, Shugo Ikeda, Tatsuma D. Matsuda, Etsuji Yamamoto, Yoshinori Haga, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 10 )   2008年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Specific heat measurements on a series of ternary compound RCu2Si2 (R: La, Pr, Nd, Sin, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) single crystals have been performed by the quasi-adiabatic heat Pulse method in the wide temperature range from 0.1 to 80 K. Almost all the compounds show antiferromagnetic orderings at low temperatures. We found the first-order like very sharp specific heat peaks in RCu2Si2 with R = Gd, Tb, Dy, Ho, and Er. Especially, the antiferromagnetic ordering in DyCu2Si2 is found to be a first-order transition. Front the analyses of the temperature dependence of magnetic entropy, we confirmed that the total splitting energy of the crystalline electric field (CEF) scheme of R3+ ion in RCu2Si2 is about 100 K in all the compounds studied here, except for YbCu2Si2. In addition, we observed the nuclear specific heat at low temperatures and estimated the magnitude of internal effective magnetic field H-eff at the nucleus.

    DOI: 10.1143/JPSJ.77.104710

    Web of Science

    researchmap

  • Evolution of an Unconventional Superconducting State inside the Antiferromagnetic Phase of CeNiGe3 under Pressure: A Ge-73-Nuclear-Quadrupole-Resonance Study 査読

    Atsushi Harada, Hidekazu Mukuda, Yoshio Kitaoka, Arumugam Thamizhavel, Yusuke Okuda, Rikio Settai, Yoshichika Onuki, Kouhei M. Itoh, Eugene E. Haller, Hisatomo Harima

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 10 )   2008年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report a Ge-73 nuclear-quadrupole-resonance (NQR) Study on novel evolution of unconventional superconductivity in antiferromagnetic (AFM) CeNiGe3. The measurements of the Ge-73-NQR spectrum and the nuclear spin-lattice relaxation rate (1/T-1) have revealed that the unconventional superconductivity evolves inside a commensurate AFM phase around the pressure (P) where Neel temperature T-N exhibits its maximum at 8.5 K. The superconducting transition temperature T-SC has been found to be enhanced with increasing T-N, before reaching the quantum critical point at which the AFM order collapses. Above T-SC, the AFM structure transits from an incommensurate spin-density-wave order to a commensurate AFM order at T similar to 2 K. accompanied by a longitudinal spin-density fluctuation. With regard to heavy-fermion compounds, these novel phenomena have hitherto never been reported in the P-T phase diagram.

    DOI: 10.1143/JPSJ.77.103710

    Web of Science

    researchmap

  • The de Haas-van Alphen oscillation and fermi surface properties of YCu <inf>2</inf>Si<inf>2</inf>

    Nguyen Duc Dung, Nguyen Duc Dung, Tatsuma D. Matsuda, Shugo Ikeda, Etsuji Yamamoto, Yoshinori Haga, Yuji Takeda, Toyoaki Endo, Yusuke Doi, Rikio Settai, Hisatomo Harima, Yoshichika Onuki, Yoshichika Onuki

    Journal of the Physical Society of Japan   77 ( 9 )   94702 - 094702-6   2008年9月

     詳細を見る

    記述言語:英語   出版者・発行元:一般社団法人日本物理学会  

    We have succeeded in growing a high-quality single crystal of a non-4f reference compound YCu2Si2 for a heavy-fermion superconductor CeCu2Si2, and observed the de Haas-van Alphen (dHvA) oscillation. The detected dHvA branches in YCu2Si 2 indicate that the Fermi surfaces are multiply connected, and the dHvA frequencies are in the range from 9 × 106 to 2 × 108 Oe. These dHvA branches are found to be well explained by the results of energy band calculations. The corresponding cyclotron masses are light, ranging from 0.4 to 1:5m0, and are consistent with the electronic specific heat coefficient of 2.2 mJ/(K2·mol). ©2008 The Physical Society of Japan.

    DOI: 10.1143/JPSJ.77.094702

    Scopus

    CiNii Article

    CiNii Books

    researchmap

  • Specific-heat study on the noncentrosymmetric heavy-fermion superconductor CePt3Si 査読

    Tetsuya Takeuchi, Masahiko Tsujino, Takashi Yasuda, Shin Hashimoto, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE KOREAN PHYSICAL SOCIETY   53 ( 2 )   1041 - 1045   2008年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KOREAN PHYSICAL SOC  

    Specific-heat measurements were performed on a high-quality single crystal of CePt3Si without inversion symmetry in the tetragonal crystal structure. We observed distinct peaks in the specific-heat C at the superconducting transition temperature T-c = 0.46 K and the antiferromagnetic ordering temperature T-N = 2.25 K, compared to the previous data, indicating an improvement of the sample quality. The temperature dependence of the electronic specific-heat coefficient C-e/T below about 0.3 K is well described by the equation of C-e/T = gamma(s) + beta T-s with gamma(s) = 34.1 mJ/K-2.Mol and beta(s) = 1290 mJ/K-3.mol, evidencing the existence of line nodes in the superconducting energy gap. Furthermore, the electronic specific-heat coefficient gamma(s) in the superconducting state indicates a nonlinear magnetic field dependence gamma(s)(H) proportional to root H, which also supports the presence of line nodes.

    DOI: 10.3938/jkps.53.1041

    Web of Science

    researchmap

  • Unconventional superconductivity in f-electron systems 査読

    Y. Onuki, R. Settai, T. Takeuchi, Y. Haga, E. Yamamoto, N. Tateiwa, M. Nakashima, H. Shishido, T. C. Kobayashi, D. Aoki

    JOURNAL OF THE KOREAN PHYSICAL SOCIETY   53 ( 2 )   1034 - 1040   2008年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KOREAN PHYSICAL SOC  

    We report pressure-induced superconductivity in antiferromagnetic cerium compounds and a ferromagnetic uranium compound, focusing on the relation between the superconducting state and the Fermi surface instability in CeRhIn5 and the huge upper critical field H-c2 in CeIrSi3 without inversion symmetry in the crystal structure. The pairing interaction is well correlated with ferromagnetism, as well as antiferromagnetism or antiferromagnetic fluctuations. In the recently discovered superconductor NpPd5Al2, superconductivity is found to be located in the vicinity of an antiferromagnetically ordered state. The upper critical field H-c2 is strongly supressed by the large paramagneic effect, and the corresponding magnetization curve indicates a step-like increase at H-c2, producing a first-order phase transition.

    Web of Science

    researchmap

  • Field-induced antiferromagnetism and upper critical field in pressure-induced superconductor CeRhIn5 査読

    Yuki Ida, Rikio Settai, Yuuki Ota, Fuminori Honda, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 8 )   2008年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    An antiferromagnet CeRhIn5 is well known to be changed into a superconductor by applying pressure P. Its electronic state is also clarified to be changed at the critical pressure P-c similar or equal to 2.5 GPa under magnetic fields. We measured the low-temperature electrical resistivity of CeRhIn5 in magnetic fields up to 17T and at pressures LIP to 2.45 GPa, and constructed phase diagrams. At P = 2.45 GPa, which is close to P-c similar or equal to 2.5 GPa. there are four kinds of phases, namely, the paramagnetic, superconducting, superconducting and antiferromagnetic, and antiferromagnetic phases in the temperature vs magnetic field phase diagram. The antiferromagnetic phase is found to be induced in the superconducting phase under magnetic fields and expanded in magnetic fields higher than the upper critical field in Superconductivity. Interestingly, the anisotropy of the upper critical field in CeRhIn5 is found to be different from that in a similar non-magnetic heavy-fermion superconductor CeCoIn5, revealing the anisotropic paramagnetic Suppression of the upper critical field.

    DOI: 10.1143/JPSJ.77.084708

    Web of Science

    researchmap

  • Fermi surface properties and unconventional superconductivity in rare earth, uranium and transuranium compounds 査読

    Y. Onuki, R. Settai, H. Shishido, S. Ikeda, T. D. Matsuda, E. Yamamoto, Y. Haga, D. Aoki, H. Harima, H. Harima, H. Yamagami

    JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS   10 ( 7 )   1535 - 1563   2008年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATL INST OPTOELECTRONICS  

    We studied the various kinds of electronic states in the f-electron systems of the cubic RX(3) and AnX(3) compounds and the tetragonal RTX(5) and AnTX(5) compounds (R: rare earth, An: Th, U, Np, Pu, T: transition metal, X: Al, Ga, In, Si, Ge, Sn) through the de Haas-van Alphen experiment and the energy band calculation. The former compounds are three dimensional in the electronic states, while the latter compounds are quasi-two dimensional. Pressure experiments were also carried out for antiferromagnets CeIn(3) and CeRhIn(5) to change the electronic state from the antiferromagnetically ordered state to the non-magnetic state, crossing the critical pressure region where the Neel temperature becomes zero. Around this critical pressure region, d-wave superconductivity is induced, and a marked change of the Fermi surface properties from the 4-localized state to the 4f-itinerant state occurs at this critical pressure, revealing the first-order phase transition.

    Web of Science

    researchmap

  • Huge upper critical field and electronic instability in pressure-induced superconductor CeIrSi3 without inversion symmetry in the crystal structure 査読

    Rikio Settai, Yuichiro Miyauchi, Tetsuya Takeuchi, Florence Levy, Ilya Sheikin, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 7 )   2008年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured low-temperature electrical resistivity in a magnetic field as a function of pressure, and studied the superconducting property of CeIrSi3 with a non-centrosymmetric tetragonal structure. CeIrSi3 is an antiferromagnet with a Neel temperature T-N = 5.0 K at ambient pressure, but the antiferromagnetic ordering disappears completely at a pressure P-c = 2.25 GPa. Superconductivity appears in a wide pressure region from 1.8 to about 3.5 GPa, with a maximum transition temperature T-sc similar or equal to 1.6 K at P-c* similar or equal to 2.63 GPa. At around P-c*, the upper critical field H-c2 for the magnetic field H along the [0 01] direction is not destroyed by spin polarization based on Zeeman coupling but possesses an upturn curvature below 1K, revealing a divergent tendency of H-c2 at P-c*, with a huge H-c2(0) similar or equal to 450 kOe. On the other hand, the upper critical field for H parallel to [110] indicates the tendency of Pauli paramagnetic suppression, with H-c2(0) = 95 kOe at 2.65 GPa. This might be a combined phenomenon between the electronic instability at P-c* and the characteristic superconducting property without inversion symmetry in the tetragonal structure.

    DOI: 10.1143/JPSJ.77.073705

    Web of Science

    researchmap

  • Magnetotransport properties governed by antiferromagnetic fluctuations in the heavy-fermion superconductor CeIrIn(5) 査読

    Y. Nakajima, H. Shishido, H. Nakai, T. Shibauchi, M. Hedo, Y. Uwatoko, T. Matsumoto, R. Settai, Y. Onuki, H. Kontani, Y. Matsuda

    PHYSICAL REVIEW B   77 ( 21 )   2008年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    In quasi-two-dimensional Ce(Ir,Rh)In(5) system, it has been suggested that the phase diagram contains two distinct domes with different heavy-fermion superconducting states. Here, we report the systematic pressure dependence of the electron transport properties in the normal state of CeRh(0.2)Ir(0.8)In(5) and CeIrIn(5), which locates in first and second superconducting domes, respectively. We observed non-Fermi liquid behavior at low temperatures in both compounds, including nonquadratic T dependence of the resistivity, large enhancement of the Hall coefficient, and the violation of the Kohler rule in the magnetoresistance. We show that the cotangent of the Hall angle cot Theta(H) varies as T(2), and the magnetoresistance is quite scaled well by the Hall angle as Delta rho(xx)/rho(xx)proportional to tan(2) Theta(H). The observed transport anomalies are common features of CeMIn(5) (M=Co, Rh, and Ir) and high-T(c) cuprates, which suggest that the anomalous transport properties observed in CeIrIn(5) are mainly governed by the antiferromagnetic spin fluctuations not by the Ce-valence fluctuations, which have been proposed to be the possible origin for the second superconducting dome.

    DOI: 10.1103/PhysRevB.77.214504

    Web of Science

    researchmap

  • Magnetic and superconducting properties of CeTX3 (T : transition metal and X : Si and Ge) with non-centrosymmetric crystal structure 査読

    Tomoya Kawai, Hiroshi Muranaka, Marie-Aude Measson, Tetsuya Shimoda, Yusuke Doi, Tatsuma D. Matsuda, Yoshinori Haga, Georg Knebel, Gerard Lapertot, Dai Aoki, Jacques Flouquet, Tetsuya Takeuchi, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 6 )   2008年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We grew single crystals of non-centrosymmetric compounds CeTSi3 and CeTGe3 (T: transition metal), and studied the magnetic properties by measuring the electrical resistivity, magnetic susceptibility and magnetization. We also studied the effect of pressure on the electronic states in antiferromagnets CeTGe3 (T: Co, Rh, Ir) by measuring the resistivity under pressure. No noticeable change of the Neel temperature was observed up to 8 GPa in CeRhGe3 and CeIrGe3, which are far from the magnetic quantum critical point. On the other hand, the Neel temperature in CeCoGe3 was strongly decreased as a function of pressure, and pressure-induced superconductivity was observed in the pressure region from 5.4GPa to about 7.5 GPa. The slope of upper critical field H,2 at 6.5 GPa is found to be extremely large, with an upturn curvature of H,2 with decreasing temperature: -dH,2/dT = 200kOe/K at the superconducting transition temperature T,,, = 0.69 K, revealing unconventional superconductivity.

    DOI: 10.1143/JPSJ.77.064716

    Web of Science

    researchmap

  • Split Fermi surface properties of LaTGe3 (T : transition metal) and PrCoGe3 with the non-centrosymmetric crystal structure 査読

    Tomoya Kawai, Hiroshi Muranaka, Toyoaki Endo, Nguyen Duc Dung, Yusuke Doi, Shugo Ikeda, Tatsuma D. Matsuda, Yoshinori Haga, Hisatomo Harima, Rikio Setta, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 6 )   2008年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing single crystals of LaTGe3 (T: Fe, Co, Rh, Ir) and PrCoGe3 with the non-centrosymmetric tetragonal crystal structure, and studied the split Fermi surface properties and the magnitude of the antisymmetric spin-orbit interaction 2 vertical bar alpha p perpendicular to vertical bar. The 2 vertical bar alpha p perpendicular to vertical bar value is found to vary when LaTGe3 is changed from T = Co, Rh to Ir, but remains unchanged in LaIrX3 from X = Si to Ge. It is found that this 2 vertical bar alpha p perpendicular to vertical bar value is large in LaIrSi3 and LaIrGe3: 2 vertical bar alpha p perpendicular to vertical bar = 460 K in LaCoGe3, 510 K in LaRhGe3, 1100 K in LaIrSi3, and 1090 K in LaIrGe3 for the main outer orbits named alpha of bands 69 and 70 electron Fermi surfaces, for example. This is due to the large effective atomic number of Ir and a large distribution of the radial wave function of Ir-5d electrons close to the nuclear center, compared with those of Co and Rh. In the case of a paramagnet PrCoGe3 and LaFeGe3 with the relatively large cyclotron mass, the corresponding 2 vertical bar alpha p perpendicular to vertical bar value is found to become small: 2 vertical bar alpha p perpendicular to vertical bar= 280 and 460 K for main orbits ot in PrCoGe3 and LaCoGe3, respectively, and 130 K for main orbits in LaFeGe3.

    DOI: 10.1143/JPSJ.77.064717

    Web of Science

    researchmap

  • Single crystal growth and de Haas-van Alphen effect in Lu2Rh3Ga9 with quasi-two-dimensional electronic state 査読

    Nguyen Duc Dung, Tatsuma D. Matsuda, Yoshinori Haga, Shugo Ikeda, Etsuji Yamamoto, Toyoaki Endo, Rikio Settai, Hisatomo Harima, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 6 )   2008年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing a single crystal of a layered compound Lu2Rh3Ga9 with an Y2Co3Ga9-type orthorhombic crystal structure by the Ga-flux method. The lattice, positional, and thermal parameters were determined by single-crystal x-ray diffraction measurement. We also measured the electrical resistivity, specific heat, and de Haas-van Alphen (dHvA) effect. The detected dHvA branches were well explained by the results of full potential linear augmented plane-wave (LAPW) energy band calculations. The electronic state was found to be quasi-two-dimensional, indicating nearly cylindrical Fermi surfaces along the [001] direction.

    DOI: 10.1143/JPSJ.77.064708

    Web of Science

    researchmap

  • High-quality single crystal growth and Fermi surface properties in f-electron systems 査読

    Y. Onuki, R. Settai, H. Shishido, S. Ikeda, T. D. Matsuda, E. Yamamoto, Y. Haga, D. Aoki, H. Harima, H. Yamagami

    JOURNAL OF CRYSTAL GROWTH   310 ( 7-9 )   1859 - 1866   2008年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    High-quality single crystals of rare earth and actinide compounds were grown by using several kinds of techniques such as the Czochralski method, flux method, chemical transport method and Bridgman method, together with purification of a uranium ingot by the solid state electrotransport method. For these single crystals, the de Haas-van Alphen experiment was carried out to clarify the Fermi surface properties, focusing on the quasi-two-dimensional electronic state of RTX(5) (R: rare earth, T: transition metal, X: In and Ga) and AnTX(5) (An: Th, U, Np and Pu), which were compared with the results of the energy band calculation. (C) 2007 Published by Elsevier B.V.

    DOI: 10.1016/j.jcrysgro.2007.09.032

    Web of Science

    researchmap

  • Pressure-induced superconductivity in antiferromagnet CePd5Al2 査読

    Fuminori Honda, Marie-Aude Measson, Yasunori Nakano, Naohisa Yoshitani, Etsuji Yamamoto, Yoshinori Haga, Tetsuya Takeuchi, Hiroshi Yamagami, Katsuya Shimizu, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77 ( 4 )   2008年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    A layered compound CePd5Al2, which is an analog of a heavy fermion superconductor NpPd5Al2, is found to be an antiferromagnet with an easy-axis along the tetragonal [001] direction but becomes superconductive in the pressure region from 9 to 12GPa, with the superconducting transition temperature, T-sc = 0.57 K and the upper critical field at 0 K, H-c2(0) = 2.5 kOe, at 10.8 GPa. The quasi-two dimensional Fermi surfaces are also theoretically calculated for CePd5Al2 on the basis of the 4f-itinerant band model.

    DOI: 10.1143/JPSJ.77.043701

    Web of Science

    researchmap

  • Unconventional superconductivity and antiferromagnetic quantum phase transition in CeRhIn5 : In-115-NQR study under pressure 査読

    M. Yashima, S. Kawasaki, H. Mukuda, Y. Kitaoka, H. Shishido, R. Settai, Y. Onuki

    PHYSICA B-CONDENSED MATTER   403 ( 5-9 )   914 - 916   2008年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report on the pressure (P)-induced phase diagram of antiferromagnetism (AFM) and superconductivity (SC) which emerges at their border at zero magnetic field. The nuclear-quadrupole-resonance (NQR) measurements have revealed that AFM can take place in the superconducting state with T-c similar to 2.1 K at P = 2.05 GPa and the AFM quantum phase transition (QPT) occurs near P = 2.1 GPa. These results reveal the existence of the tetracritical point in the P-T phase diagram of AFM and SC in CeRnIn5. We also found the gapless nature in the uniformly coexisting phase of AFM and SC, indicating an intimate relationship between AFM and SC. (c) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physb.2007.10.062

    Web of Science

    researchmap

  • Enhancement of superconducting transition temperature due to the strong antiferromagnetic spin fluctuations in the noncentrosymmetric heavy-fermion superconductor CeIrSi3: A Si-29 NMR study under pressure 査読

    H. Mukuda, T. Fujii, T. Ohara, A. Harada, M. Yashima, Y. Kitaoka, Y. Okuda, R. Settai, Y. Onuki

    PHYSICAL REVIEW LETTERS   100 ( 10 )   2008年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report a Si-29 NMR study on the pressure-induced superconductivity (SC) in an antiferromagnetic (AFM) heavy-fermion compound CeIrSi3 without inversion symmetry. In the SC state at P=2.7-2.8 GPa, the temperature (T) dependence of the nuclear-spin lattice relaxation rate 1/T-1 below T-c exhibits a T-3 behavior without any coherence peak just below T-c, revealing the presence of line nodes in the SC gap. In the normal state, 1/T-1 follows a root T-like behavior, suggesting that the SC emerges under the non-Fermi-liquid state dominated by AFM spin fluctuations enhanced around a quantum critical point. The reason why the maximum T-c in CeIrSi3 is relatively high among the Ce-based heavy-fermion superconductors may be the existence of the strong AFM spin fluctuations. We discuss the comparison with the other Ce-based heavy-fermion superconductors.

    DOI: 10.1103/PhysRevLett.100.107003

    Web of Science

    researchmap

  • Pressure-induced unconventional superconductivity in the heavy-fermion antiferromagnet CeIn3: An In115 -NQR study under pressure 査読

    S. Kawasaki, M. Yashima, Y. Kitaoka, K. Takeda, K. Shimizu, Y. Oishi, M. Takata, T. C. Kobayashi, H. Harima, S. Araki, H. Shishido, R. Settai, Y. Onuki

    Physical Review B - Condensed Matter and Materials Physics   77 ( 6 )   2008年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We report on pressure-induced unconventional superconductivity (SC) in the heavy-fermion (HF) antiferromagnet CeIn3 by means of nuclear-quadrupole- resonance (NQR) studies conducted under a high pressure. The temperature (T) and pressure (P) dependences of the In-NQR spectra have revealed a first-order quantum-phase transition (QPT) from antiferromagnetism (AFM) to paramagnetism (PM) at a critical pressure Pc =2.46 GPa at which AFM disappears with a minimum value of TN (Pc) =1.2 K. High-energy x-ray scattering measurements under P show a progressive decrease in the lattice density without any change in the crystal structure, whereas an increase in the NQR frequency (νQ) indicates an increase in the hybridization between 4f electrons and conduction electrons, which stabilizes the HF-PM state. This competition between the AFM phase where TN is reduced and the formation of the HF-PM phase triggers the first-order QPT at Pc =2.46 GPa. Despite the lack of an AFM quantum critical point in the P-T phase diagram, we highlight the fact that unconventional SC occurs in both phases of AFM and PM. The measurements of the nuclear spin-lattice relaxation rate 1/T1 in the AFM phase have provided evidence for the uniformly coexisting AFM+SC phase. Remarkably, the significant increase in 1/T1 upon cooling in the AFM phase has revealed the development of low-lying magnetic excitations down to Tc in the AFM phase
    it is indeed relevant to the onset of the uniformly coexisting AFM+SC phase. In the HF-PM phase where AFM fluctuations are not developed, 1/T1 decreases without the coherence peak just below Tc, followed by a power-law-like T dependence that indicates an unconventional SC with a line-node gap. Remarkably, Tc has a peak around Pc in the HF-PM phase as well as in the AFM phase. In other words, an SC dome exists with a maximum value of Tc =230 mK around Pc, indicating that the origin of the pressure-induced HF SC in CeIn3 is not relevant to AFM spin fluctuations but to the emergence of the first-order QPT in CeIn3. These phenomena observed in CeIn3 should be understood in terms of the first-order QPT because these new phases of matter are induced by applying P. When the AFM critical temperature is suppressed at the termination point of the first-order QPT, Pc =2.46 GPa, the diverging AFM spin-density fluctuations emerge at the critical point from AFM to PM. The results with CeIn3 leading to a new type of quantum criticality deserve further theoretical investigations. © 2008 The American Physical Society.

    DOI: 10.1103/PhysRevB.77.064508

    Scopus

    researchmap

  • Ground state magnetic structure of Ce2Ni3Ge5 査読

    F. Honda, N. Metoki, T. D. Matsuda, Y. Haga, A. Thamizhavel, Y. Okuda, R. Settai, Y. Onuki

    JOURNAL OF ALLOYS AND COMPOUNDS   451 ( 1-2 )   504 - 506   2008年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    We have carried out neutron diffraction experiments on Ce2Ni3Ge5 single crystal. Ce2Ni3Ge5 orders antiferromagnetically below T-N=5K and exhibits a successive transition at T* = 4.3 K. We have confirmed that the ground state antiferromagnetic structure is characterized with the propagation vector q = [010]. We have revealed that this magnetic structure stabilizes only below V = 4.3 K from the simultaneous neutron diffraction and electrical resistivity measurements, contrary to the previously reported neutron powder diffraction result. From the analysis of magnetic reflection intensities, we suggest that the ground state magnetic structure is a canted AF structure, where the moments orient about 200 tilted from the a-axis in the ab-plane. The obtained AF components are 0.45 mu(B)/Ce along the a-axis and 0.15 mu(B)/Ce along the b-axis. It is suggested that the high temperature phase is characterized with another magnetic phase having a different propagation vector, which is not determined in the present study. (C) 2007 Published by Elsevier B.V.

    DOI: 10.1016/j.jallcom.2007.04.191

    Web of Science

    researchmap

  • de Haas-van Alphen Effect in EuRu4Sb12 査読

    Hitoshi Sugawara, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77   297 - 299   2008年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report the first successful observation of the de Haas-van Alphen (dHvA) effect in Eu-based filled skutterudite EuRu4Sb12 which shows a ferromagnetic transition at T-C = 3.3 K. The dHvA frequencies and those angular dependences are highly different from those for the trivalent compounds such as LaRu4Sb12 and PrRu4Sb12. This fact is consistent with the results of magnetic susceptibility and the X-ray absorption near edge spectroscopy measurements which have revealed a nearly divalent Eu electronic configuration. The cyclotron effective masses have been estimated ranging from 1.6(m0) to 2.6(m0).

    DOI: 10.1143/JPSJS.77SA.297

    Web of Science

    researchmap

  • Electrical Properties and dHvA Experiments in Ferromagnet Ce3Al11 査読

    Chandrashekhar S. Garde, Fuminori Honda, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77   356 - 358   2008年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    High-quality single crystals of Ce3Al11 with the orthorhombic crystal structure have been grown by the Al-flux method. Signatures for ferromagnetic and antiferromagnetic orderings at T-C = 6.3K and T-N = 3.2K, respectively, have been observed in the electrical resistivity. On application of pressure, the Neel temperature T-N decreases rapidly and goes to zero around 3GPa. On the other hand, the Curie temperature T-C is found to be robust against pressure up to 4GPa. Further, dHvA oscillations have been obtained for magnetic field along the [0 1 0] direction. A cyclotron mass m(c)* as large as 28m(0) (m(0): rest mass of an electron) has been observed for one of the dHvA branches, indicating the heavy fermion nature of Ce3Al11.

    DOI: 10.1143/JPSJS.77SA.356

    Web of Science

    researchmap

  • de Haas-van Alphen Effect in LaOs4P12 査読

    Yoshinori Iwahashi, Hitoshi Sugawara, Ko-ichi Magishi, Takahito Saito, Kuniyuki Koyama, Rikio Settai, Yoshichika Onuki, Gerald Giester, Peter Rogl

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77   219 - 221   2008年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have succeeded in observing the de Haas-van Alphen effect in LaOs4P12 which is a superconductor with the transition temperature T-C = 2.0 K and a reference compound for PrOs4P12. We have found the multiply-connected and almost spherical Fermi surfaces whose cyclotron effective masses are ranging 1.1-4.7m(0). The Fermi surface topology is close to that of PrOs4P12, indicating the localized nature of 4f-electrons in PrOs4P12. From the comparison with LaOs4P12, the large mass enhancement in PrOs4P12 has been clarified.

    DOI: 10.1143/JPSJS.77SA.219

    Web of Science

    researchmap

  • de Haas-van Alphen study of the Pr-based filled skutterudite PrOs4P12 査読

    Hitoshi Sugawara, Yoshinori Iwahashi, Ko-ichi Magishi, Takahito Saito, Kuniyuki Koyama, Hisatomo Harima, Daisuke Kikuchi, Hideyuki Sato, Toyoaki Endo, Rikio Settai, Yoshichika Onuki, Naoki Wada, Hisashi Kotegawa, Tatsuo C. Kobayashi

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77   108 - 113   2008年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have succeeded in observing the de Haas-van Alphen effect in PrOs4P12 which shows no anomaly down to 50 mK in contrast to PrFe4P12 and PrRu4P12. The Fermi surface (FS) topology is reasonably explained by the energy band structure calculation based on a full potential linearized augmented-plane-wave method within the local-density-approximation. Whereas the localized nature of 4f-electrons, we have confirmed a highly enhanced cyclotron effective mass up to 18m(0) in PrOs4P12, which is enhanced 3.8 times compared to that of LaOs4P12. No nesting property with q = (1, 0, 0) in the FS of PrOs4P12 has been confirmed, which suggests both the 4f-electron's contribution and the FS nesting property play the role for the phase transitions in PrFe4P12 and PrRu4P12.

    DOI: 10.1143/JPSJS.77SA.108

    Web of Science

    researchmap

  • Heavy Fermion Superconductivity with the Strong Pauli Paramagnetic Effect on NpPd5Al2 査読

    Dai Aoki, Yoshinori Haga, Tatsuma D. Matsuda, Naoyuki Tateiwa, Shugo Ikeda, Yoshiya Homma, Hironori Sakai, Yoshinobu Shiokawa, Etsuji Yamamoto, Akio Nakamura, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77   159 - 164   2008年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the electrical resistivity, specific heat, magnetic susceptibility and magnetization in the first Np-based superconductor NpPd5Al2 with the tetragonal crystal structure. NpPd5Al2 is a paramagnet and becomes the superconductivity at T-c = 4.9 K. The large electronic specific heat coefficient of gamma = 200mJ/K(2)mol at T-c indicates that NpPd5Al2 is a heavy fermion superconductor. The upper critical field Hc2 is large and highly anisotropic: H-c2(0) = 37 kOe for H parallel to [100] and H-c2(0) = 143 kOe for H parallel to [001]. Although the initial slope of H-c2 at Tc is very large, H-c2 is strongly suppressed against the magnetic field for both field direction, indicating the existence of strong Pauli paramagnetic effect. Furthermore, the magnetization curve shows the step-like behaviors at H-c2, corresponding to the first order transition. The d-wave superconductivity with the spin-singlet state is most likely realized in NpPd5Al2.

    DOI: 10.1143/JPSJS.77SA.159

    Web of Science

    researchmap

  • De Haas-van alphen effecs using a micro-cantilever: application to LaFeGe3 査読

    Rikio Settai, Tomoya Kawai, Toyoaki Endo, Hiroshi Muranaka, Yuusuke Doi, Yoshichika Onuki, Hisatomo Harima

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77   345 - 347   2008年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have performed de Haas-van Alphen (dHvA) experiments using micro-cantilever on small single crystal of LaFeGe3 with longest dimension less than 0.1 mm. Detected dHvA frequencies using micro-cantilever shows a good agreement with the result of the band calculation. The micro-cantilever is a hopeful device to detect the dHvA effect for a very small single crystals less than 0.1mm

    DOI: 10.1143/JPSJS.77SA.345

    Web of Science

    researchmap

  • Superconducting Properties of CePt3Si and CeIrSi3 without Inversion Symmetry in the Crystal Structure 査読

    Yoshichika Onuki, Yuuichiro Miyauchi, Masahiko Tsujino, Yuki Ida, Rikio Settai, Tetsuya Takeuchi, Naoyuki Tateiwa, Tatsuma D. Matsuda, Yoshinori Haga, Hisatomo Harima

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77   37 - 42   2008年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The upper critical field Hc(2) in superconductivity was investigated for CePt3Si and CeIrSi3 without inversion symmetry in the tetragonal structure. A significant anisotropy of Hc(2) between H vertical bar vertical bar [0 0 1] and H vertical bar vertical bar [1 0 0] was not observed in CePt3Si even at 0.6 GPa as well as ambient pressure, where the Neel temperature with T-N = 2.3 K at ambient pressure becomes zero at 0.6 GPa. The similar result was observed at 1.95 GPa in CeIrSi3, where antiferromagnetism and superconductivity coexist, while a large anisotropy of Hc(2) in CeIrSi3 was observed with increasing pressure: Hc(2)(0) = 300-400 kOe for H vertical bar vertical bar [0 0 1] and Hc(2)(0) = 95 kOe for H vertical bar vertical bar [1 1 0] at 2.65 GPa, which is higher than the critical pressure P-c = 2.25 GPa. A large value of Hc(2) for H vertical bar vertical bar [0 0 1] in CeIrSi3 might become an experimental evidence of the spin-triplet superconductivity in the non-centrosymmetric structure. It is also remarkable that CeIrSi3 is a strong coupling superconductor and the electronic specific heat coefficient is approximately unchanged as a function of pressure even at P-c, which is highly different from the divergent mass enhancement at Pc in a pressure-induced heavy fermion superconductor CeRhIn5.

    DOI: 10.1143/JPSJS.77SA.37

    Web of Science

    researchmap

  • Super Clean Sample of URu2Si2 査読

    Tatsuma D. Matsuda, Dai Aoki, Shugo Ikeda, Eetsuji Yamamoto, Yoshinori Haga, Hitoshi Ohkuni, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77   362 - 364   2008年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing a high-quality single crystal of URu2Si2 by the Czochralski pulling method and applying the solid state electro-transport method under ultrahigh vacuum. The sample quality strongly depends on the position in the ingot. For some parts of this ingot, the electrical resistivity, specific heat and de Haas-van Alplhen effect were measured. The electrical resistivity of the surface sample clearly indicates a T-linear temperature dependence below 5 K. The mean free path in this sample was determined by the de Haas-van Alphen effect to be 11000 angstrom.

    DOI: 10.1143/JPSJS.77SA.362

    Web of Science

    researchmap

  • Effect of Pressure and Magnetic Field on the Superconducting State of a Heavy Fermion Superconductor NpPd5Al2 査読

    Fuminori Honda, Rikio Settai, Dai Aoki, Yoshinori Haga, Tatsuma D. Matsuda, Naoyuki Tateiwa, Shugo Ikeda, Yoshiya Homma, Hironori Sakai, Yoshinobu Shiokawa, Etsuji Yamamoto, Akio Nakamura, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   77   339 - 341   2008年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have carried out the electrical resistivity measurements under high pressures and high magnetic fields in NpPd5Al2 in order to investigate a quantum critical behavior and the stability of the superconducting phase. A T-linear dependence of the electrical resistivity is changed into the Fermi liquid relation of rho similar to AT(2) under the magnetic fields, and A value indicates a divergent feature around the upper critical field H-c2, indicating the existence of a field-tuned quantum critical point (QCP) around H-c2. With increasing pressure, the superconducting transition temperature T-sc decreases and becomes zero above 5.7 GPa, together with a decrease of the upper critical field, indicating that the electronic state of NpPd5Al2 is located in the vicinity of QCP at ambient pressure and deviates from QCP with increasing pressure. Furthermore, we have constructed the superconducting phase diagram at 3.71 GPa.

    DOI: 10.1143/JPSJS.77SA.339

    Web of Science

    researchmap

  • Large heat capacity jump at the superconducting transiton temperature in the non-centrosymmetric superconductor CeIrSi3 under high pressure. 査読

    Naoyuki Tateiwa, Yoshinori Haga, Tatsuma D. Matsuda, Shugo Ikeda, Etsuji Yamamoto, Yusuke Okuda, Yuichiro Miyauchi, Rikio Settai, Yoshichika Onuki

    JOINT 21ST AIRAPT AND 45TH EHPRG INTERNATIONAL CONFERENCE ON HIGH PRESSURE SCIENCE AND TECHNOLOGY   121   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We investigated the pressure-induced superconductor CeIrSi3 without inversion center under high pressure. The electrical resistivity and ac heat capacity were measured in the same run for the same sample. The critical pressure of the antiferromagnetic state was determined to be P-c = 2.25 GPa. The heat capacity C-ac shows both antiferromagnetic and superconducting transitions at pressures close to P-c. The co-existence of the antiferromagnetism and superconductivity is discussed. The superconducting region is extended up to about 3.5 GPa. The superconducting transition temperature T-sc shows a maximum value of 1.6 K around 2.5 - 2.7 GPa. At 2.58 GPa, a large heat capacity anomaly was observed at T-sc = 1.59 K. The jump of the heat capacity in the form of Delta C-ac/C-ac(T-sc) is 5.7 +/- 0.1. This is the largest observed value among all superconductors studied previously, suggesting the strong-coupling superconductivity in CeIrSi3.

    DOI: 10.1088/1742-6596/121/5/052001

    Web of Science

    researchmap

  • Thermoelectric response near a quantum critical point: The case of CeCoIn5 査読

    K. Izawa, K. Behnia, Y. Matsuda, H. Shishido, R. Settai, Y. Onuki, J. Flouquet

    PHYSICAL REVIEW LETTERS   99 ( 14 )   2007年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We present a study of thermoelectric coefficients in CeCoIn5 down to 0.1 K and up to 16 T in order to probe the thermoelectric signatures of quantum criticality. In the vicinity of the field-induced quantum critical point, the Nernst coefficient nu exhibits a dramatic enhancement without saturation down to the lowest measured temperature. The dimensionless ratio of the Seebeck coefficient to the electronic specific heat shows a minimum at a temperature close to threshold of the quasiparticle formation. Close to T-c(H), in the vortex-liquid state, the Nernst coefficient behaves anomalously in puzzling contrast with other superconductors and standard vortex dynamics.

    DOI: 10.1103/PhysRevLett.99.147005

    Web of Science

    researchmap

  • Striking similarities between HTSC and quasi-2D HFCeRIn5 査読

    Koichi Izawa, Y. Nakajima, Y. Kasahara, R. Bel, K. Behnia, H. Shishido, R. Settai, Y. Onuki, H. Kontani, Y. Matsuda

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   460   145 - 148   2007年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report our measurements of transport coefficients of quasi-2D HF CeRIn5 in the normal state, in the vicinity of a QCP and in the superconducting state. In the normal state, we observed a T-linear resistivity, a T-2-dependence of cot theta(H) (theta(H) is the Hall angle), the violation of Kohler's rule, and a giant Nernst coefficient. In the superconducting state, on the other hand, we found a rapid increase of the quasiparticle (QP) mean free path as the temperatures is reduced below T-c. The density of states (DOS) of delocalized QPs obtained from the thermal Hall coefficient is consistent with a d-wave pairing symmetry. Moreover, the angular dependence of thermal conductivity indicates that the gap function has a d-wave symmetry with line nodes perpendicular to the ab-plane. These results bear a striking resemblance to those obtained for the high-T-c cuprates. This similarity implies that the fluctuation and excitation spectrum near a 2D antiferromagnetic QCP could be universal. (c) 2007 Published by Elsevier B.V.

    DOI: 10.1016/j.physc.2007.04.004

    Web of Science

    researchmap

  • Strong-coupling superconductivity of CeIrSi3 with the non-centrosymmetric crystal structure 査読

    Naoyuki Tateiwa, Yoshinori Haga, Tatsuma D. Matsuda, Shugo Ikeda, Etsuji Yamamoto, Yusuke Okuda, Yuichiro Miyauchi, Rikio Settai, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   76 ( 8 )   2007年8月

     詳細を見る

    記述言語:英語   出版者・発行元:PHYSICAL SOC JAPAN  

    We studied the pressure-induced superconductor CeIrSi3 with the non-centrosymmetric tetragonal structure under high pressure. The electrical resistivity and ac heat capacity were measured in the same run for the same sample. The critical pressure was determined to be P-c = 2.25 GPa, where the antiferromagnetic state disappears. The heat capacity C-ac shows both antiferromagnetic and superconducting transitions at pressures close to P, On the other hand, the superconducting region is extended to high pressures of up to about 3.5 GPa, with the maximum transition temperature T-sc = 1.6 K around 2.5-2.7GPa. At 2.58GPa, a large heat capacity anomaly was observed at T-sc = 1.59K. The jump of the heat capacity in the form Of Delta C-ac/C-ac(T-sc) is 5.7 +/- 0.1. This is the largest observed value among previously reported superconductors, indicating the strong-coupling superconductivity. The electronic specific heat coefficient at T-sc is, however, approximately unchanged as a function of pressure, even at P-c.

    DOI: 10.1143/JPSJ.76.083706

    Web of Science

    researchmap

  • Non-centro symmetric heavy fermion superconductivity in CeCoGe3 査読

    R. Settai, Y. Okuda, I. Sugitani, Y. Onuki, T. D. Matsuda, Y. Haga, H. Harima

    INTERNATIONAL JOURNAL OF MODERN PHYSICS B   21 ( 18-19 )   3238 - 3245   2007年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    We measured the electrical resistivity under pressure for an antiferromagnet CeCoGe3 without inversion symmetry in the tetragonal crystal structure. The Neel temperature T-N1 = 21 K at ambient pressure decreases monotonically with increasing pressure, and becomes zero at about 5.5 GPa. Superconductivity appears above 4.3GPa, with a superconduting transition temperature T-SC = 0.72 K and a large upper critical field H-c2(0) = 7 T at 5.6 GPa. The large upper critical field H-c2 (0) =7 T exceeds the Pauli limitting field H-p (similar or equal to 1.86T(SC))=1.3 T as in CePt3Si, CeRhSi3 and CeIrSi3. The large slope of H-c2 at T-SC, -dH(c2)/dT = 18 T/K, at 5.6 GPa indicates the heavy-fermion superconductivity in CeCoGe3.

    DOI: 10.1142/S0217979207044287

    Web of Science

    researchmap

  • Quantum phase diagram of antiferromagnetism and superconductivity with a tetracritical point in CeRhIn5 in zero magnetic field 査読

    M. Yashima, S. Kawasaki, H. Mukuda, Y. Kitaoka, H. Shishido, R. Settai, Y. Onuki

    PHYSICAL REVIEW B   76 ( 2 )   2007年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report on a pressure-temperature phase diagram of antiferromagnetism (AFM) and superconductivity (SC) in CeRhIn5 studied by the nuclear-quadrupole-resonance measurements under pressure. It is demonstrated that an AFM phase transition takes place inside the superconducting state. This result reveals that a tetracritical point exists in the phase diagram of AFM and SC at zero magnetic field. The finding of unconventional SC characteristics in the uniformly coexisting phase of AFM and SC suggests that both phases may be mediated by the same magnetic interaction.

    DOI: 10.1103/PhysRevB.76.020509

    Web of Science

    researchmap

  • Single crystal growth and Fermi surface property in ThRhIn5 査読

    Tatsuma D. Matsuda, Yoshinori Haga, Etsuji Yamamoto, Shugo Ikeda, Hiroaki Shishido, Rikio Settai, Hisatomo Harima, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   76 ( 6 )   2007年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing a high-quality single crystal of ThRhIn5 with the HoCoGa5-type tetragonal crystal structure by the In-flux method. The lattice parameters, positional parameters and thermal parameters were determined from single-crystal x-ray diffraction measurements. We also measured the electrical resistivity and de Haas-van Alphen (dHvA) effect. Main dHvA branches are very similar to those of the 4f-itinerant heavy fermion superconductor CeCoIn5, but the cyclotron effective masses are by one to two orders of magnitude smaller than those of CeCoIn5. These Fermi surface properties are well explained by the FLAPW energy band calculations.

    DOI: 10.1143/JPSJ.76.064712

    Web of Science

    researchmap

  • Pressure-induced antiferromagnetic superconductivity in CeNiGe3: A 73Ge-NQR study under pressure 査読

    A. Harada, S. Kawasaki, H. Mukuda, Y. Kitaoka, A. Thamizhavel, Y. Okuda, R. Settai, Y. Onuki, K. M. Itoh, E. E. Haller, H. Harima

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   310 ( 2 )   614 - 616   2007年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report on antiferromagnetic (AF) properties of pressure-induced superconductivity in CeNiGe3 via the Ge-73 nuclear-quadrupole-resonance (NQR) measurements under pressure (P). The NQR-spectrum measurements have revealed that the incommensurate antiferromagnetic ordering is robust against increasing P with the increase of ordered moment and ordering temperature. Nevertheless the measurements of nuclear spin-lattice relaxation rate (1/T-1) have pointed to the onset of superconductivity as a consequence of Ce-4f electrons delocalized by applying P. The emergence of superconductivity under the development of AF order suggests that a novel type of superconducting mechanism works in this compound. (c) 2006 Elsevier B. V. All rights reserved.

    DOI: 10.1016/j.jmmm.2006.10.883

    Web of Science

    researchmap

  • Magnetic and electronic properties in CeTSi3 and CeTGe3 (T : transition metal) 査読

    T. Shimoda, Y. Okuda, Y. Takeda, Y. Ida, Y. Miyauchi, T. Kawai, T. Fujie, I. Sugitani, A. Thamizhavel, T. D. Matsuda, Y. Haga, T. Takeuchi, M. Nakashima, R. Settai, Y. Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   310 ( 2 )   308 - 309   2007年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We investigated the magnetic properties of CeTSi3 (T: Ru, Os, Co, Rh, Ir, Pd and Pt) and CeTGe3 (T: Co, Rh and Ir) by measuring their electrical resistivity and magnetic susceptibility. CeRuSi3, CeOsSi3 and CeCoSi3 do not order magnetically, with a large Kondo temperature of about 200 K. The other compounds order antiferromagnetically, and are very similar to each other in their magnetic and electronic properties, which is related to a large crystalline electric. field (CEF) splitting energy of the 4f electron, about 500K in CeIrSi3. (c) 2006 Published by Elsevier B.V.

    DOI: 10.1016/j.jmmm.2006.10.055

    Web of Science

    researchmap

  • Hall effect in the quasi two-dimensional strongly correlated metal CeMIn5 (M = Co, Rh) 査読

    Y. Nakajima, H. Shishido, H. Nakai, T. Shibauchi, K. Izawa, K. Behnia, H. Hedo, Y. Uwatoko, T. Matsumoto, R. Settai, Y. Onuki, H. Kontani, Y. Matsuda

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   310 ( 2 )   334 - 336   2007年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report on the evolution of the Hall effect in heavy fermion compounds CeMIn5 (M = Co, Rh), ranging from antiferromagnetic metal to Fermi liquid regime through non-Fermi liquid regime by applying pressure. We found that anomalous transport properties of CeMIn5 are strikingly similar to that of high-T-c cuprates. We also found that the magnitude of Hall coeffi. cient appears to diverge near an antiferromagnetic quantum critical point. These results strongly suggest that unusual transport properties of CeMIn5 are dominated by anisotropic scattering due to strong spin. uctuations. (c) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jmmm.2006.10.028

    Web of Science

    researchmap

  • Anomalous quasiparticle transport and superclean superconducting state of CeCoIn5 査読

    Y. Kasahara, Y. Nakajima, K. Izawa, Y. Matsuda, K. Behnia, H. Shishido, R. Settai, Y. Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   310 ( 2 )   569 - 571   2007年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    To investigate the quasiparticle dynamics in the superconducting state of quasi-two dimensional heavy fermion superconductor CeCoIn5, thermal conductivity tensor is measured. We obtained the quasiparticle mean free path and the density of states separately by using the combination of longitudinal thermal conductivity and thermal Hall angle. The quasiparticle mean free path increases dramatically below T-c in zero magnetic field. The density of states and the scaling relation of thermal Hall conductivity are consistent with d-wave symmetry. We also argue that CeCoIn5 is in the superclean regime. These results highlight the anomalous superconducting state in CeCoIn5 with striking similarities with high-T-c cuprates. (c) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jmmm.2006.10.154

    Web of Science

    researchmap

  • Magnetic-field modulation of the Josephson effect in heavy-fermion superconductor CeIrIn5 査読

    A. Sumiyama, Y. Tsuji, Y. Oda, H. Shishido, R. Settai, Y. Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   310 ( 2 )   599 - 601   2007年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The Josephson effect between a single-crystal CeIrIn5 and an s-wave superconductor has been investigated for current. ows parallel to the [1 0 0] and [1 1 0] axes of CeIrIn5. The magnetic-field modulation of the Josephson critical current has shown a nearly ideal Fraunhofer pattern in the [1 0 0] direction and a small deviation from that pattern in the [1 1 0] direction. The clear anisotropy, which has been reported for YBa2Cu3O7-delta indicating the d- wave superconductivity, was not observed in this study. (c) 2006 Elsevier B. V. All rights reserved.

    DOI: 10.1016/j.jmmm.2006.10.245

    Web of Science

    researchmap

  • Pressure effect of electrical resistivity and AC specific heat in CePtAl 査読

    M. Nakashima, T. Ueda, K. Shimizu, H. Nakashima, A. Thamizhavel, N. Tateiwa, Y. Haga, M. Hedo, Y. Uwatoko, R. Settai, Y. Onuki, K. Izawa, G. Knebel, B. Salce, J. Flouquet

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   310 ( 2 )   E9 - E11   2007年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We measured the electrical resistivity and AC-specific heat for a canted ferromagnet CePtAl under pressures using a diamond-anvil pressure cell. With increasing pressure, the magnetic ordering temperature T-C1 increases monotonously, becomes constant above 8GPa and then starts to decrease steeply in a narrow pressure region from 10.3 to 10: 9 GPa, indicating the first-order like phase transition. The similar pressure dependence of T-C1 was obtained in the AC-specific heat measurement. (c) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jmmm.2006.10.056

    Web of Science

    researchmap

  • Synthesis, crystal structure and magnetic properties of Yb8Ag18.5Al47.5, Yb2Pd2Cd and Yb-1.35Pd2Cd0.65 査読

    S. K. Dhar, R. Settai, Y. Onuki, A. Galatanu, Y. Haga, P. Manfrinetti, M. Pani

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   308 ( 1 )   143 - 152   2007年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report the synthesis of three new Yb-based compounds, Yb8Ag18.5Al47.5 (Yb8Cu17Al49-type, tetragonal tI74-14/mmm), Yb2Pd2Cd (Mo2B2Fe-type, tetragonat tP10-P4/mbm) and Yb1.35Pd2Cd0.65 (MnCu2Al-type, cubic cF16-Fm (K) over barm). The crystal symmetry of these compounds has been determined and the complete structural characterisation carried out by single crystal and powder diffraction techniques. Two symmetry in-equivalent sites are available for the Yb ions in Yb8Ag18.5Al47.5 and Yb1.35Pd2Cd0.65. The 4f levels of the Yb ions are appreciably hybridised in Yb8Ag18.5Al47.5 and to a lesser extent in Yb2Pd2Cd as inferred from the magnetisation and heat capacity data. Signatures of heavy fermion behaviour are observed in the heat capacity data of Yb2Pd2Cd in which the heat capacity, C/T, increases at low temperatures attaining a value of approximate to 600 mJ/mol K-2 at 1.8 K. The electrical resistivity of Yb2Pd2Cd follows a linear variation with temperature, T, between 1.4 and 5 K, thus indicating a possible non-Fermi liquid behaviour. In contrast, Yb ions are trivalent in Yb1.35Pd2Cd0.65 and order magnetically near 1.4 K. (c) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jmmm.2006.05.013

    Web of Science

    researchmap

  • Pressure-induced superconductivity in CeNiGe<inf>3</inf>

    H. Kotegawa, T. Miyoshi, K. Takeda, S. Fukushima, H. Hidaka, K. Tabata, T. C. Kobayashi, M. Nakashima, A. Thamizhavel, R. Settai, Y. Onuki

    Physica B: Condensed Matter   378-380 ( SPEC. ISS. )   419 - 420   2006年5月

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    An antiferromagnet CeNiGe3, which exhibits a quantum critical point at PC ∼ 6 - 7 GPa, shows the superconductivity in wide pressure range of 1.7 - 9.3 GPa. In addition to the superconductivity around PC, the sharp superconducting transition can be observed by both the resistivity and the susceptibility measurements at lower pressure region far apart from PC, where 4f-localized picture seems to be still dominant. Such a superconductivity is a first example in the f-electron systems. © 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physb.2006.01.147

    Scopus

    researchmap

  • Evolution of Hall coefficient in two-dimensional heavy fermion CeCoIn5 査読

    Y Nakajima, K Izawa, Y Matsuda, K Behnia, H Kontani, M Hedo, Y Uwatoko, T Matsumoto, H Shishido, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   75 ( 2 )   2006年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report on the pressure dependence of the Hall coefficient RH in quasi-2D heavy fermion CeCoIn5. At ambient pressure, below a temperature associated with the emergence of non-Fermi liquid properties, RH is anomalously enhanced. We found that the restoration of the Fermi liquid state with applied pressure leads to a gradual suppression of this dramatic enhancement. Moreover, the enhancement in RH was found to be confined to an intermediate temperature window, where inelastic electron-electron scattering is dominant. Our results strongly support the presence of cold and hot spots on the Fermi surface probably due to anisotropic scattering by antiferromagnetic fluctuations, which may also prove relevant for the debate on the anomalous normal-state properties of high-T-c cuprates.

    DOI: 10.1143/JPSJ.75.023705

    Web of Science

    researchmap

  • Change of the electronic states in CeIn3, CeRhIn5 and CePt3Si tuned by pressure 査読

    Y Onuki, R Settai, H Shishido, Kubo, I, Y Yasuda, K Betsuyaku, H Harima

    JOURNAL OF ALLOYS AND COMPOUNDS   408   27 - 32   2006年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    We have studied a change of the electronic states in antiferromagnets CeIn3, CeRhIn5 and CePt3Si via the de Haas-van Alphen experiments. The critical pressure P-c, where the Neel temperature becomes zero, is P-c similar or equal to 2.5 GPa in CeIn3 with the cubic crystal structure, in which the narrow pressure region superconductivity appears below a superconducting transition temperature T-sc = 0.2 K. In the pressure region P &gt; P-c, we detected a main Fermi surface with the cyclotron mass m*(c) = 53m(0), which most likely corresponds to a nearly spherical Fermi surface in the paramagnetic state, namely a 4f-itinerant Fermi surface. The Fermi surface in the antiferromagnet CeRhIn5 with the tetragonal crystal structure is similar to that of LaRhIn5, consisting of two kinds of nearly cylindrical Fermi surfaces. We observed a drastic change of the Fermi surface from 4f-localized (LaRhIn5) to 4f-itinerant (CeCoIn5) Fermi surfaces at P-c similar or equal to 2.4 GPa. The cyclotron mass increases intensively above 1.6 GPa where superconductivity sets in. CePt3 Si with the tetragonal crystal structure without inversion symmetry is highly different from CeIn3 and CeRhIn5 in magnetism and superconductivity. It orders antiferromagnetically below T-N = 2.3 K and becomes superconductive below T-sc = 0.6 K at ambient pressure. With increasing pressure, the cyclotron mass is found to be reduced, together with a steep decrease of T-N and Tsc, where P-c is most likely about 1.5 GPa in CePt3Si. The heavy fermion state Of CePt3Si is realized at ambient pressure. (c) 2005 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jallcom.2005.04.101

    Web of Science

    researchmap

  • Evidence for novel pairing state in noncentrosymmetric superconductor CePt3Si: Si-29-NMR knight shift study 査読

    M Yogi, H Mukuda, Y Kitaoka, S Hashimoto, T Yasuda, R Settai, TD Matsuda, Y Haga, Y Onuki, P Rogl, E Bauer

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   75 ( 1 )   2006年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report the measurements of the Si-29 Knight shift K-29 on the noncentrosymmetric heavy-fermion compound CePt3Si in which antiferromagnetism (AFM) with T-N = 2.2 K coexists with superconductivity (SC) with T-c = 0.75 K. Its spin part K-29(s), which is deduced to be K-s(c) &gt;= 0.11 and 0.16% at respective magnetic fields H = 2.0061 and 0.8671 T, does not decrease across the superconducting transition temperature Tc for the field along the c-axis. The temperature dependence of nuclear spin-lattice relaxation of Pt-195 below T-c has been accounted for by a Cooper pairing model with a two-component order parameter composed of spin-singlet and spin-triplet pairing components. From this result, it is shown that the Knight-shift data are consistent with the occurrence of the two-component order parameter for CePt3Si.

    DOI: 10.1143/JPSJ.75.013709

    Web of Science

    researchmap

  • In-115-NQR study of antiferromagnetism and superconductivity in CeRhIn5 and CeIn3 under pressure 査読

    S Kawasaki, M Yashima, H Kotegawa, T Mito, Y Kawasaki, GQ Zheng, Y Kitaoka, H Shishido, S Araki, D Aoki, Y Haga, R Settai, Y Onuki

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   67 ( 1-3 )   497 - 499   2006年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We report the novel phase diagram of superconductivity (SC) and anti ferromagnetism (AFM) in heavy-fermion (HF) pressure(P)-induced superconductors CeRhIn5 and CeIn5 through nuclear-quadrupole-resonance (NQR) measurements under P. The P-induced superconductivity in CeRhIn5 coexists with AFM on a microscopic level in P = 1.5-1.9 GPa. By contrast, in CeIn3, the P-induced phase separation of AFM and paramagnetism (PM) takes place without any trace of a quantum phase transition. The outstanding finding is that SC sets in at both the phases magnetically separated into AFM and PM in P=2.28-2.5 GPa. (c) 2005 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jpcs.2005.10.043

    Web of Science

    researchmap

  • Pt-195 NMR study on noncentrosymmetric heavy-fermion superconductor CePt3Si 査読

    M Yogi, Y Kitaoka, S Hashimoto, T Yasuda, R Settai, TD Matsuda, Y Haga, Y Onuki, P Rogl, E Bauer

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   67 ( 1-3 )   522 - 524   2006年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We report on magnetic and novel superconducting properties in heavy-fermion (HF) noncentrosymmetric compound CePt3Si via the measurement of Pt-195 nuclear spin-lattice relaxation rate 1/T-1. This compound reveals the uniform coexistence of antiferromagnetism (T-N = 2.2 K) and superconductivity (T-c =0.75 K). CePt3Si is the first HF superconductor that reveals a peak in 1/T-1 just below T-c and, additionally, does not follow the T-3 law that was observed for most unconventional HF superconductors. The novel relaxation behavior found below T-c may be relevant with a possible novel SC state being realized in the noncentrosymmetric CePt3Si. (c) 2005 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jpcs.2005.10.070

    Web of Science

    researchmap

  • de Haas-van Alphen effect and the metamagnetic transition based on the quadrupole moment in PrCu <sub>2</sub>

    M. Abliz, R. Settai, P. Ahmet, D. Aoki, K. Sugiyama, Y. Ōnuki

    Philosophical Magazine B   2006年

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1080/13642819708202330

    Web of Science

    researchmap

  • Anomalous quasiparticle transport in the superconducting state of CeCoIn5 査読

    Y. Kasahara, Y. Nakajima, K. Izawa, Y. Matsuda, K. Behnia, H. Shishido, R. Settai, Y. Onuki

    Physical Review B - Condensed Matter and Materials Physics   72 ( 21 )   2005年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We report on a study of thermal Hall conductivity κxy in the superconducting state of CeCoIn5. The scaling relation and the density of states of the delocalized quasiparticles, both obtained from κxy, are consistent with d-wave superconducting symmetry. The onset of superconductivity is accompanied by a steep increase in the thermal Hall angle, pointing to a striking enhancement in the quasiparticle mean free path. This enhancement is drastically suppressed in a very weak magnetic field. These results highlight that CeCoIn5 is unique among superconductors. A small Fermi energy, a large superconducting gap, a short coherence length, and a long mean free path all indicate that CeCoIn5 is clearly in the superclean regime (εF Δ ξ), in which a peculiar vortex state is expected. © 2005 The American Physical Society.

    DOI: 10.1103/PhysRevB.72.214515

    Scopus

    researchmap

  • Anomalous quasiparticle transport in the superconducting state of CeCoIn5 査読

    Y Kasahara, Y Nakajima, K Izawa, Y Matsuda, K Behnia, H Shishido, R Settai, Y Onuki

    PHYSICAL REVIEW B   72 ( 21 )   2005年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report on a study of thermal Hall conductivity kappa(xy) in the superconducting state of CeCoIn5. The scaling relation and the density of states of the delocalized quasiparticles, both obtained from kappa(xy), are consistent with d-wave superconducting symmetry. The onset of superconductivity is accompanied by a steep increase in the thermal Hall angle, pointing to a striking enhancement in the quasiparticle mean free path. This enhancement is drastically suppressed in a very weak magnetic field. These results highlight that CeCoIn5 is unique among superconductors. A small Fermi energy, a large superconducting gap, a short coherence length, and a long mean free path all indicate that CeCoIn5 is clearly in the superclean regime (epsilon(F)/Delta &lt;center dot/xi), in which a peculiar vortex state is expected.

    DOI: 10.1103/PhysRevB.72.214515

    Web of Science

    researchmap

  • Single crystal growth and Fermi surface properties of ThIn3 査読

    TD Matsuda, Y Haga, S Ikeda, H Shishido, R Settai, H Harima, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   74 ( 12 )   3276 - 3282   2005年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have succeeded in growing a high-quality single crystal of ThIn3 with the cubic structure by the Influx method and measured the electrical resistivity, magnetic susceptibility and de Haas-van Alphen (dHvA) effect. Several dHvA branches were observed, ranging from 5.2 x 10(6) to 1.7 x 10(8) Oe. The Fermi surface consists of a nearly spherical Fermi surface and a multiply-connected Fermi surface. The corresponding cyclotron effective masses are small, ranging from 0.31 to 1.4 m(0). These Fermi surface properties are well explained by the energy band calculations based on the FLAPW method.

    DOI: 10.1143/JPSJ.74.3276

    Web of Science

    researchmap

  • Effect of pressure on electronic states in canted ferromagnet CePtAl 査読

    T Ueda, M Nakashima, M Hedo, Y Uwatoko, H Nakashima, A Thamizhavel, TD Matsuda, Y Haga, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   74 ( 12 )   3393 - 3394   2005年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    DOI: 10.1143/JPSJ.74.3393

    Web of Science

    researchmap

  • Change of the Fermi surface across the critical pressure in CeIn3: The de Haas-van Alphen study under pressure 査読

    R Settai, T Kubo, T Shiromoto, D Honda, H Shishido, K Sugiyama, Y Haga, TD Matsuda, K Betsuyaku, H Harima, TC Kobayashi, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   74 ( 11 )   3016 - 3026   2005年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have studied a change of the Fermi surface in an antiferromagnet CeIn3 via the de Haas-van Alphen experiment under pressure up to 3 GPa. With increasing pressure P, the Neel temperature T-N = 10 K decreases and becomes zero at a critical pressure P-c similar or equal to 2.6 GPa. In the pressure region P &gt; P,, we have observed a large main Fermi surface named a, which indicates that the electronic state of 4f electron in CeIn3 changes from localized to itinerant at P-c, as observed in the similar antiferromagnets CeRh2Si2 and CeRhIn5. The cyclotron effective mass m(c)(*) of this main Fermi surface is extremely enhanced around P-c: m(c)(*) similar or equal to 60m(0) at 2.7 GPa for the magnetic field along the (100) direction.

    DOI: 10.1143/JPSJ.74.3016

    Web of Science

    researchmap

  • Josephson effect between CePt3Si and an s-wave superconductor 査読

    A Sumiyama, K Nakatsuji, Y Tsuji, Y Oda, T Yasuda, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   74 ( 11 )   3041 - 3045   2005年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Josephson critical current I-c between a single crystal CePt3Si and Al has been measured for the junctions on the CePt3Si surface perpendicular to the a and c axes. In the magnetic-field dependence of I-c a dominant maximum peak at zero field has been observed only for the junction on the a-axis face thus far, indicating that the Josephson effect is allowed at least for current flow parallel to the a axis. This result places a restriction on the representations of the order parameter in the noncentrosymmetric superconductor CePt3Si.

    DOI: 10.1143/JPSJ.74.3041

    Web of Science

    researchmap

  • New high field state of flux line lattice in CeCoIn5 査読

    Y Kasahara, T Watanabe, K Izawa, T Sakakibara, CJ van der Beek, T Hanaguri, M Nohara, H Takagi, H Shishido, R Settai, Y Onuki, Y Matsuda

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   426   36 - 40   2005年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have measured the ultrasound velocity of quasi-two-dimensional superconductor CeCoIn5 with extremely large Pauli paramagnetic susceptibility. The results indicate that the new high field superconducting phase, which is revealed by the recent heat capacity measurements, is characterized by the unusual softening of flux line lattice. The softening is most likely due to the collapse of the flux line lattice tilt modulus and transition to quasi-two-dimensional vortex state. These results provide a strong evidence that the high field phase is the Fulde-Ferrell-Larkin-Ovchinnikov phase, in which the order parameter is spatially modulated and has planar nodes aligned perpendicularly to the vortices. (c) 2005 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physc.2005.02.018

    Web of Science

    researchmap

  • Multiple superconducting phases in heavy fermion superconductors 査読

    Y Matsuda, K Izawa, T Watanabe, Y Kasahara, Y Nakajima, T Sakakibara, CJ van der Beek, M Nohara, T Hanaguri, H Takagi, J Goryo, K Maki, P Thalmeier, S Osaki, H Sugawara, H Sato, H Shishido, R Settai, Y Onuki

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   66 ( 8-9 )   1365 - 1369   2005年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We show that in recently discovered heavy fermion superconductors, quasi two-dimensional CeCoIn5 and skutterudite PrOs4Sb12, multiple superconducting phases with different symmetries manifest themselves below T-c. The ultrasound velocity measurements revealed that in CeCoIn5 the Fulde-Ferrel-Larkin-Ovchinikov phase, in which the order parameter is spatially modulated and has planar nodes aligned perpendicular to the vortices, appears at low temperature and high field. The angle resolved magnetothermal transport measurements revealed that in PrOs4Sb12 a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state. These results open up a new realm for the study of the superconductivity with multiple phases. (c) 2005 Published by Elsevier Ltd.

    DOI: 10.1016/j.jpcs.2005.05.012

    Web of Science

    researchmap

  • Novel pressure phase diagram of heavy fermion superconductor CePt3Si investigated by ac calorimetry 査読

    N Tateiwa, Y Haga, TD Matsuda, S Ikeda, T Yasuda, T Takeuchi, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   74 ( 7 )   1903 - 1906   2005年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The pressure dependences of the antiferromagnetic and superconducting transition temperatures have been investigated by ac heat capacity measurement under high pressures for the heavy-fermion superconductor CePt3Si without inversion symmetry in the tetragonal structure. The Neel temperature T-N = 2.2 K decreases with increasing pressure and becomes zero at the critical pressure P-AF similar or equal to 0.6 GPa. On the other hand, the superconducting phase exists in a wider pressure region from ambient pressure to about 1.5 GPa. The pressure phase diagram of CePt3Si is thus very unique and has never been reported before for other heavy fermion superconductors.

    DOI: 10.1143/JPSJ.74.1903

    Web of Science

    researchmap

  • Bulk-sensitive photoemission spectroscopy of Pr-based filled skutterudites 査読

    A Yamasaki, S Imada, A Sekiyama, M Tsunekawa, T Nanba, C Dallera, L Braicovich, TL Lee, H Sugawara, H Sato, C Sekine, Shirotani, I, R Settai, Y Onuki, H Harima, S Suga

    JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA   144   621 - 623   2005年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Bulk electronic structures of Pr-based filled skutterudites and their reference materials have been investigated by bulk-sensitive photoemission spectroscopy using soft and hard X-rays. For Pr 3d-4f resonance, a strong intensity in the vicinity of Fermi level (EF) is observed only for PrFe4P12. Furthermore, PrFC4P12 has the significant spectral weight of the vertical bar 3d(9)4f(3)&gt; final state in Pr 3d core-level spectrum. We interpret that the observed prominent intensity just below EF arises from a Kondo resonance due to the strong hybridization between the Pr 4f and conduction states. (c) 2005 Elsevier B.V. All Rights Reserved.

    DOI: 10.1016/j.elspec.2005.01.025

    Web of Science

    researchmap

  • Line nodes in the superconducting gap function of noncentrosymmetric CePt3Si 査読

    K Izawa, Y Kasahara, Y Matsuda, K Behnia, T Yasuda, R Settai, Y Onuki

    PHYSICAL REVIEW LETTERS   94 ( 19 )   2005年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    The superconducting gap structure of recently discovered heavy fermion CePt3Si without spatial inversion symmetry was investigated by thermal transport measurements down to 40 mK. In zero field a residual T-linear term was clearly resolved as T -&gt; 0, with a magnitude in good agreement with the value expected for a residual normal fluid with a nodal gap structure, together with a T-2 dependence at high temperatures. With an applied magnetic field, the thermal conductivity grows rapidly, in dramatic contrast to fully gapped superconductors, and exhibits one-parameter scaling with T/root(H) over bar. These results place an important constraint on the order parameter symmetry; that is, CePt3Si is most likely to have line nodes.

    DOI: 10.1103/PhysRevLett.94.197002

    Web of Science

    researchmap

  • Pressure dependence of the first-order superconducting phase transition in CeCoIn5 査読

    T Tayama, Y Namai, T Sakakibara, M Hedo, Y Uwatoko, H Shishido, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   74 ( 4 )   1115 - 1118   2005年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The pressure dependence of the first-order phase transition (FOPT) at the upper critical field H-c2 in CeCoIn5 has been Studied by magnetization measurements. The FOPT is found to persist at pressures at least up to 1.5 GPa in the c axis and up to 1.38 GPa in the a axis. With increasing pressure, the anisotropy of H-c2 becomes stronger, and the condensation energy decreases significantly. We also observed a notable peak effect near H-c2 under pressure. Our results suggest that the FOPT cannot be accounted for by Pauli limiting alone.

    DOI: 10.1143/JPSJ.74.1115

    Web of Science

    researchmap

  • Ordered magnetic and quadrupolar states under hydrostatic pressure in orthorhombic PrCu2 査読

    T Naka, LA Ponomarenko, A de Visser, A Matsushita, R Settai, Y Onuki

    PHYSICAL REVIEW B   71 ( 2 )   2005年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    We report magnetic susceptibility and electrical resistivity measurements under hydrostatic pressure up to 2 GPa on single-crystalline PrCu2, which exhibits the pressure-induced Van Vleck paramagnet-to-antiferromagnet transition at 1.2 GPa. The measured anisotropy in the susceptibility shows that the ordered 4f moments lie in the ac plane in the pressure-induced magnetic state. We propose that remarkable pressure effects on the susceptibility and resistivity are due to changes in the quadrupolar state of O-2(2) and/or O-2(0) under pressure. We present a simple analysis in terms of the singlet-singlet model.

    DOI: 10.1103/PhysRevB.71.024408

    Web of Science

    researchmap

  • Fermi surface of LaRu4 P12: A clue to the origin of the metal-insulator transition in PrRu4 P12 査読

    S. R. Saha, H. Sugawara, Y. Aoki, H. Sato, Y. Inada, H. Shishido, R. Settai, Y. Onuki, H. Harima

    Physical Review B - Condensed Matter and Materials Physics   71 ( 13 )   2005年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We report the de Haas-van Alphen (dHvA) effect and magnetoresistance in the filled-skutterudite superconductor LaRu4 P12, which is a reference material of PrRu4 P12 that exhibits a metal-insulator (M-I) transition at TMI 60 K. The observed dHvA branches for the main Fermi surface (FS) are well explained by the band-structure calculation, using the full potential linearized augmented-plane-wave method with the local-density approximation, suggesting a nesting instability with q= (1,0,0) in the main multiply connected FS as expected also in PrRu4 P12. Observed cyclotron effective masses of (2.6-11.8) m0, which are roughly twice the calculated masses, indicate the large mass enhancement even in the La-skutterudites. Comparing the FS between LaRu4 P12 and PrRu4 P12, an essential role of c-f hybridization cooperating with the FS nesting in driving the M-I transition in PrRu4 P12 is clarified. © 2005 The American Physical Society.

    DOI: 10.1103/PhysRevB.71.132502

    Scopus

    researchmap

  • Evidence for direct CP violation in B-0 -&gt; K+pi(-) decays 査読

    Y Chao, P Chang, K Abe, K Abe, N Abe, Adachi, I, H Aihara, K Akai, M Akatsu, M Akemoto, Y Asano, T Aso, Aulchenko, V, T Aushev, T Aziz, S Bahinipati, AM Bakich, Y Ban, M Barbero, A Bay, Bedny, I, U Bitenc, Bizjak, I, S Blyth, A Bondar, A Bozek, M Bracko, J Brodzicka, TE Browder, MC Chang, A Chen, KF Chen, WT Chen, BG Cheon, R Chistov, SK Choi, Y Choi, YK Choi, A Chuvikov, S Cole, M Danilov, M Dash, LY Dong, R Dowd, J Dragic, A Drutskoy, S Eidelman, Eiges, V, Y Enari, D Epifanov, CW Everton, F Fang, J Flanagan, S Fratina, H Fujii, Y Funakoshi, K Furukawa, N Gabyshev, A Garmash, T Gershon, A Go, G Gokhroo, B Golob, MG Perdekamp, H Guler, R Guo, J Haba, C Hagner, F Handa, K Hara, T Hara, NC Hastings, K Hasuko, K Hayasaka, H Hayashii, M Hazumi, EM Heenan, Higuchi, I, T Higuchi, L Hinz, T Hojo, T Hokuue, Y Hoshi, K Hoshina, S Hou, WS Hou, YB Hsiung, HC Huang, T Igaki, Y Igarashi, T Iijima, H Ikeda, A Imoto, K Inami, A Ishikawa, H Ishino, K Itoh, R Itoh, M Iwamoto, M Iwasaki, Y Iwasaki, R Kagan, H Kakuno, T Kamitani, JH Kang, JS Kang, P Kapusta, SU Kataoka, N Katayama, H Kawai, H Kawai, Y Kawakami, N Kawamura, T Kawasaki, N Kent, HR Khan, A Kibayashi, H Kichimi, M Kikuchi, E Kikutani, HJ Kim, HO Kim, H Kim, JH Kim, SK Kim, TH Kim, K Kinoshita, S Kobayashi, H Koiso, P Koppenburg, S Korpar, P Krizan, P Krokovny, T Kubo, R Kulasiri, S Kumar, CC Kuo, H Kurashiro, E Kurihara, A Kusaka, A Kuzmin, YJ Kwon, JS Lange, G Leder, SE Lee, SH Lee, YJ Lee, T Lesiak, J Li, A Limosani, SW Lin, D Liventsev, J MacNaughton, G Majumder, F Mandl, D Marlow, M Masuzawa, T Matsuishi, H Matsumoto, S Matsumoto, T Matsumoto, A Matyja, S Michizono, Y Mikami, T Mimashi, W Mitaroff, K Miyabayashi, Y Miyabayashi, H Miyake, H Miyata, R Mizuk, D Mohapatra, GR Moloney, GF Moorhead, T Mori, J Mueller, A Murakami, T Nagamine, Y Nagasaka, T Nakadaira, Nakamura, I, TT Nakamura, E Nakano, M Nakao, H Nakayama, H Nakazawa, Z Natkaniec, K Neichi, S Nishida, O Nitoh, S Noguchi, T Nozaki, A Ogawa, S Ogawa, Y Ogawa, K Ohmi, Y Ohnishi, T Ohshima, N Ohuchi, K Oide, T Okabe, S Okuno, SL Olsen, Y Onuki, W Ostrowicz, H Ozaki, P Pakhlov, H Palka, CW Park, H Park, KS Park, N Parslow, LS Peak, M Pernicka, JP Perroud, M Peters, LE Piilonen, A Poluektov, FJ Ronga, N Root, M Rozanska, H Sagawa, M Saigo, S Saitoh, Y Sakai, H Sakamoto, H Sakaue, TR Sarangi, M Satapathy, N Sato, T Schietinger, O Schneider, J Schumann, C Schwanda, AJ Schwartz, T Seki, S Semenov, K Senyo, Y Settai, R Seuster, ME Sevior, T Shibata, H Shibuya, T Shidara, B Shwartz, Sidorov, V, Siegle, V, JB Singh, A Somov, N Soni, R Stamen, S Stanic, M Staric, R Sugahara, A Sugi, T Sugimura, A Sugiyama, K Sumisawa, T Sumiyoshi, S Suzuki, SY Suzuki, SK Swain, O Tajima, F Takasaki, K Tamai, N Tamura, K Tanabe, M Tanaka, M Tawada, GN Taylor, Y Teramoto, XC Tian, S Tokuda, SN Tovey, K Trabelsi, T Tsuboyama, T Tsukamoto, K Uchida, S Uehara, T Uglov, K Ueno, Y Unno, S Uno, Y Ushiroda, G Varner, KE Varvell, S Villa, CC Wang, CH Wang, JG Wang, MZ Wang, M Watanabe, Y Watanabe, L Widhalm, QL Xie, BD Yabsley, A Yamaguchi, H Yamamoto, N Yamamoto, S Yamamoto, T Yamanaka, Y Yamashita, M Yamauchi, H Yang, P Yeh, J Ying, K Yoshida, M Yoshida, Y Yuan, Y Yusa, H Yuta, SL Zang, CC Zhang, J Zhang, LM Zhang, ZP Zhang, Y Zheng, Zhilich, V, T Ziegler, D Zontar, D Zurcher

    PHYSICAL REVIEW LETTERS   93 ( 19 )   2004年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report evidence for direct CP violation in the decay B-0--&gt;K(+)pi(-) with 253 fb(-1) of data collected with the Belle detector at the KEKB e(+)e(-) collider. Using 275x10(6) B(B) over bar pairs we observe a B--&gt;K(+/-)pi(-/+) signal with 2140+/-53 events. The measured CP violating asymmetry is A(CP)(K(+)pi(-))=-0.101+/-0.025(stat)+/-0.005(syst), corresponding to a significance of 3.9sigma including systematics. We also search for CP violation in the decays B+--&gt;K(+)pi(0) and B+--&gt;pi(+)pi(0). The measured CP violating asymmetries are A(CP)(K(+)pi(0))=0.04+/-0.05(stat)+/-0.02(syst) and A(CP)(pi(+)pi(0))=-0.02+/-0.10(stat)+/-0.01(syst), corresponding to the intervals -0.05&lt; A(CP)(K(+)pi(0))&lt;0.13 and -0.18&lt; A(CP)(pi(+)pi(0))&lt;0.14 at 90% confidence level.

    DOI: 10.1103/PhysRevLett.93.191802

    Web of Science

    researchmap

  • Pressure-induced superconductivity in UIr 査読

    T Akazawa, H Hidaka, H Kotegawa, TC Kobayashi, T Fujiwara, E Yamamoto, Y Haga, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 11 )   3129 - 3134   2004年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Pressure-induced superconductivity is found in UIr without inversion symmetry. The pressure-temperature phase diagram has been investigated by means of the electrical resistivity and magnetization measurements under high pressure. The phase diagram consists of two magnetic phases, the Ising-like ferromagnetic phase (FM1) at low pressures and another magnetic phase (FM2) with the small ferromagnetic component along the [101] direction at high pressures. Superconductivity is observed in the narrow pressure range near the disappearance point of the FM2 phase, where the temperature dependence of resistivity follows the non-Fermi liquid form of T-1.6. From these experimental facts, the superconductivity is considered to be associated with the critical fluctuation with the disappearance of FM2 phase.

    DOI: 10.1143/JPSJ.73.3129

    Web of Science

    researchmap

  • Two kinds of cylindrical fermi surface determined by de Haas-van alphen experiments in NpCoGa5 査読

    D Aoki, Y Homma, Y Shiokawa, E Yamamoto, A Nakamura, Y Haga, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 10 )   2608 - 2611   2004年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in observing de Haas-van Alphen (dHvA) oscillations in an antiferromagnet NpCoGa5 with a tetragonal structure. The dHvA signal was significantly enhanced at higher fields than the metamagnetic transition field H-m (= 43 kOe for H parallel to [001]), where the antiferromagnetic state is changed into the field-induced ferromagnetic (paramagnetic) state. In the paramagnetic state, the Fermi surface was found to consist of two kinds of cylindrical main Fermi surface and small pocket Fermi surfaces. The cyclotron masses of the main Fermi surfaces were considerably large, ranging from 6 to 12 m(0). This is the first case where the Fermi surface was determined experimentally in transuranium compounds.

    DOI: 10.1143/JPSJ.73.20608

    Web of Science

    researchmap

  • Two Kinds of Cylindrical Fermi Surfce Determined by de Haas-van Alphen Experiments in NpCoGa5 査読

    D. Aoki, Y. Homma, Y.Shiokawa, E. Yamamoto, A. Nakamura, Y. Haga, R. Settai, T. Takeuchi, Y. Onuki

    J. Phys. Soc. Japan   73 ( 10 )   1 - 4   2004年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1143/JPSJ.73.2608

    researchmap

  • High-resolution angle-resolved photoemission study of LaRh3B2 査読

    Y Iida, S Souma, T Sato, T Takahashi, M Yamada, T Okubo, T Shiromoto, Y Inada, R Settai, Y Onuki

    PHYSICA B-CONDENSED MATTER   351 ( 3-4 )   271 - 273   2004年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report high-resolution angle-resolved photoemission spectroscopy of LaRh3B2, which is a nonmagnetic reference compound of RRh3B2 (R: rare-earth metals). We found two hole-like Fermi surfaces (FSs) and two electron-like FSs centered at Gamma(A) and K(H) points, respectively. The estimated volume of FSs at Gamma(A) point shows a good agreement with the LDA band calculation, while the band dispersion and the topology of FSs at K(H) point show a remarkable disagreement. (C) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physb.2004.06.023

    Web of Science

    researchmap

  • Small saturation moment due to the crystalline electric field effect for T-h site symmetry in the ferromagnet UFe4P12 査読

    TD Matsuda, A Galatanu, Y Haga, S Ikeda, E Yamamoto, M Hedo, Y Uwatoko, T Takeuchi, K Sugiyama, K Kindo, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 9 )   2533 - 2538   2004年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Electrical resistivity, specific heat, magnetic susceptibility and high-field magnetization measurements have been performed on the ferromagnet UFe4P12 with the cubic crystal structure. The ferromagnetic ordering at T-C = 3.1 K, a small saturation moment of 1.3 mu(B)/U, together with the temperature dependence of the magnetic susceptibility, are found to be well explained by considering the 5f(2) crystalline electric field schemes for T-h site symmetry and the magnetic exchange interaction.

    DOI: 10.1143/JPSJ.73.2533

    Web of Science

    researchmap

  • Magnetic and fermi surface properties of an antiferromagnet Ce3Sn7 査読

    Y Okuda, T Takeuchi, T Yamamoto, D Honda, H Shishido, A Galatanu, TD Matsuda, Y Haga, K Kindo, K Sugiyama, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 8 )   2276 - 2282   2004年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the electrical resistivity, specific heat, magnetic susceptibility, high-field magnetization, thermal expansion and magnetostriction of an antiferromagnet Ce3Sn7 with the orthorhombic crystal structure. The experimental data are found to be well explained on the basis of the crystalline electric field (CEF) 4f-scheme previously proposed by Bonnet et al. in which the two Cc atoms at the 2(a) site possess a magnetic moment of 0.36 /mu(B)/Ce and the one Ce atom at the 4(i) site possesses no magnetic moment as in a valence fluctuating compound CeSn3. We also constructed the antiferromagnetic phase diagram for the three principal directions. Furthermore, we carried out the de Haas-van Alphen experiment. Fermi surfaces are many in number but extremely small in volumes, indicating that Ce3Sn7 is a semimetal.

    DOI: 10.1143/JPSJ.73.2276

    Web of Science

    researchmap

  • Magnetic and fermi surface properties in PrRh3B2 査読

    M Yamada, Y Obiraki, T Okubo, T Shiromoto, Y Kida, M Shiimoto, H Kohara, T Yamamoto, D Honda, A Galatanu, Y Haga, T Takeuchi, K Sugiyama, R Settai, K Kindo, SK Dhar, H Harima, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 8 )   2266 - 2275   2004年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have grown a single crystal of PrRh3B2 with the hexagonal structure and measured the electrical resistivity, specific heat, de Haas-van Alphen oscillation, magnetic susceptibility, high-field magnetization, thermal expansion and magnetostriction. PrRh3B2 is not a simple ferromagnet as reported previously, but a ferrimagnet with an ordering temperature T-ord = 3.6 K. The Schottky specific heat observed around 25 K and the large anisotropy of the magnetic susceptibility and magnetization are found to be well explained by the crystalline electric field (CEF) with a large overall CEF-splitting energy of 1080 K and a strong ferromagnetic exchange interaction along the [0001] direction. The topology of the Fermi surface in PrRh3B2 is Similar to that of the non-4f reference compound LaRh3B2, exhibiting a quasi-one-dimensional character of the electronic states.

    DOI: 10.1143/JPSJ.73.2266

    Web of Science

    researchmap

  • High-field state of the flux-line lattice in the unconventional superconductor CeCoIn5 査読

    T Watanabe, Y Kasahara, K Izawa, T Sakakibara, Y Matsuda, CJ van der Beek, T Hanaguri, H Shishido, R Settai, Y Onuki

    PHYSICAL REVIEW B   70 ( 2 )   2004年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    Ultrasound velocity measurements of the unconventional superconductor CeCoIn5 with extremely large Pauli paramagnetic susceptibility reveal an unusual structural transformation of the flux-line lattice (FLL) in the vicinity of the upper critical field. The transition field coincides with that at which heat capacity measurements reveal a second-order phase transition. The lowering of the sound velocity at the transition is consistent with vortex segmentation and a crossover to quasi-two-dimensional FLL pinning. These results provide strong evidence that the high-field state is the Fulde-Ferrel-Larkin-Ovchinikov phase, in which the order parameter is spatially modulated and has planar nodes aligned perpendicular to the vortices.

    DOI: 10.1103/PhysRevB.70.020506

    Web of Science

    researchmap

  • Superconducting property in CePt3Si under pressure 査読

    T Yasuda, H Shishido, T Ueda, S Hashimoto, R Settai, T Takeuchi, TD Matsuda, Y Haga, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 7 )   1657 - 1660   2004年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have studied the superconducting property by measuring the electrical resistivity under the magnetic field and pressure for CePt3Si, which is the first antiferromagnetic heavy fermion superconductor without inversion symmetry in its tetragonal crystal structure. The upper critical field H-c2(0) is found to be approximately isotropic: H-c2(0) = 2.7 T for H || [100] and 3.2 T for H || [001]. The Neel temperature T-N = 2.3 K and the zero resistivity superconducting transition temperature T-sc similar or equal to 0.65 K decrease markedly with increasing pressure, suggesting that the present superconductivity is correlated to the anti ferromagnetic state.

    DOI: 10.1143/JPSJ.73.1657

    Web of Science

    researchmap

  • Magnetism and superconductivity in a heavy-fermion superconductor, CePt3Si 査読

    T Takeuchi, S Hashimoto, T Yasuda, H Shishido, T Ueda, M Yamada, Y Obiraki, M Shiimoto, H Kohara, T Yamamoto, K Sugiyama, K Kindo, TD Matsuda, Y Haga, Y Aoki, H Sato, R Settai, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   16 ( 28 )   L333 - L342   2004年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We have studied the magnetic and thermal properties of a single crystal of CePt3Si, which is a recently reported heavy-fermion superconductor with a superconducting transition temperature T-c = 0.75 K and a Neel temperature T-N = 2.2 K. The overall experimental data are principally explained on the basis of the crystalline electric field (CEF) scheme. Even in the antiferromagnetic state, the CEF model applies well to the characteristic features in the magnetization curve. These results indicate the existence of a localized magnetic moment at the Ce site, with a considerably reduced ordered moment of 0.16 mu(B)/Ce, and the strongly correlated conduction electrons are condensed into the superconducting state. We have also constructed the magnetic phase diagram including the superconducting phase for H parallel to [110] and [001].

    DOI: 10.1088/0953-8984/16/28/L03

    Web of Science

    researchmap

  • High-field state of the flux-line lattice in the unconventional superconductor CeCoIn5 査読

    T. Watanabe, Y. Kasahara, K. Izawa, T. Sakakibara, Y. Matsuda, C. J. Van Der Beek, T. Hanaguri, H. Shishido, R. Settai, Y. Onuki

    Physical Review B - Condensed Matter and Materials Physics   70 ( 2 )   1 - 20506   2004年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Ultrasound velocity measurements of the unconventional superconductor CeCoIn5 with extremely, large Pauli paramagnetic susceptibility reveal an unusual structural transformation of the flux-line lattice (FLL) in the vicinity of the upper critical field. The transition field coincides with that at which heat capacity measurements reveal a second-order phase transition. The lowering of the sound velocity at the transition is consistent with vortex segmentation and a crossover to quasi-two-dimensional FLL pinning. These results provide strong evidence that the high-field state is the Fulde-Ferrel-Larkin- Ovchinikov phase, in which the order parameter is spatially modulated and has planar nodes aligned perpendicular to the vortices.

    DOI: 10.1103/PhysRevB.70.020506

    Scopus

    researchmap

  • Single crystal growth of large-size and high-quality NpCoGa5 and its electrical and magnetic properties 査読

    D Aoki, Y Homma, Y Shiokawa, E Yamamoto, A Nakamura, Y Haga, R Settai, T Takeuchi, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 7 )   1665 - 1668   2004年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing a high-quality NpCoGa5 single crystal by the Ga-flux method and measured its electrical resistivity, specific heat, magnetic susceptibility and magnetization. NpCoGa5 is an antiferromagnet with a Neel temperature of 47 K. The magnetic moment of Np is directed along the [001] direction of a tetragonal crystal structure. A sharp metamagnetic transition was observed at H-m = 43 kOe for H || [001], where the antiferromagnetic state is changed to the paramagnetic state above H-m. The ordered moment was determined to be 0.74 mu(B)/Np. The magnetic properties were discussed on the basis of the crystalline electric field scheme of the 5f(4) configuration.

    DOI: 10.1143/JPSJ.73.1665

    Web of Science

    researchmap

  • The de Haas-van Alphen effect and the Fermi surface in CePt3Si and LaPt3Si 査読

    S Hashimoto, T Yasuda, T Kubo, H Shishido, T Ueda, R Settai, TD Matsuda, Y Haga, H Harima, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   16 ( 23 )   L287 - L296   2004年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We have carried out a de Hass-van Alphen (dHvA) experiment for the recently discovered CePt3Si, which is the first heavy fermion superconductor without inversion symmetry in the tetragonal crystal structure, together with a dHvA experiment for a non-4f reference compound LaPt3Si. As for LaPt3Si, several dHvA branches were observed. Among them, the two main dHvA branches with the dHvA frequency (the cyclotron effective mass) of 1.10 x 10(8) Oe (1.4 m(0)) and 8.41 x 10(7) Oe (1.5 m(0)) were found to be well explained from the FLAPW energy band calculations, corresponding to bands 64- and 63-multiply-connected hole Fermi surfaces, respectively. On the other hand, the dHvA frequencies of 10(7) Oe in CePt3Si are small in magnitude, although the corresponding cyclotron masses of 10-20 m(0) are extremely large.

    DOI: 10.1088/0953-8984/16/23/L02

    Web of Science

    researchmap

  • Heat-capacity anomalies at T-sc and T-* in the ferromagnetic superconductor UGe2 査読

    N Tateiwa, TC Kobayashi, K Amaya, Y Haga, R Settai, Y Onuki

    PHYSICAL REVIEW B   69 ( 18 )   2004年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The heat-capacity and magnetization measurements under high pressure have been carried out in a ferromagnetic superconductor UGe2. Both measurements were done using a same pressure cell in order to obtain both data for one pressure. Contrary to the heat capacity at ambient pressure, an anomaly is found in the heat capacity at the characteristic temperature T-* where the magnetization shows an anomalous enhancement under high pressure where the superconductivity appears. This suggests that a thermodynamic phase transition takes place at T-* at least under high pressure slightly below P-c(*) where T-* becomes zero. The heat-capacity anomaly associated with the superconducting transition is also investigated, where a clear peak of C/T is observed in a narrow pressure region (DeltaPsimilar to0.1 GPa) around P-c(*) contrary to the previous results of the resistivity measurement. Present results suggest the importance of the thermodynamic critical point P-c(*) for the appearance of the superconductivity.

    DOI: 10.1103/PhysRevB.69.180513

    Web of Science

    researchmap

  • De hass van Alphen effect of CeRhIn5 and CeCoIn5 under pressure 査読

    H Shishido, R Settai, S Hashimoto, Y Inada, Y Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   272   225 - 226   2004年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have studied de Hass van Alphen (dHvA) effect under pressure for a pressure-induced superconductor CeRhIn5 and a superconductor CeCoIn5. The topology of the Fermi surface in CeRhIn5 and CeCoIn5 are found to be unchanged up to 2.1 GPa and 3.1 GPa, respectively. On the other hand, the effective mass of CeRhIn5(CeCoIn5) decreases (increases) remarkably with increasing pressure. (C) 2003 Published by Elsevier B.V.

    DOI: 10.1016/j.jmmm.2003.11.087

    Web of Science

    researchmap

  • A change of the Fermi surface in CeIn3 under pressure 査読

    R Settai, T Kubo, H Shishido, TC Kobayashi, Y Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   272   223 - 224   2004年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have investigated a change of the electronic state in CeIn3 via de Haas-van Alphen (dHvA) experiments under pressure up to 2.7 GPa. The shape of a spherical Fermi surface with humps along &lt;111&gt; changes slightly at 2.5 GPa. (C) 2003 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jmmm.2003.11.200

    Web of Science

    researchmap

  • High-quality single crystal growth of UGe2 and URhGe 査読

    E. Yamamoto, Y. Haga, T. D. Matsuda, S. Ikeda, Y. Inada, R. Settai, Y. Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   272   E171 - E172   2004年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We searched for an experimental condition of crystal growth for a ferromagnetic superconductors of UGe2 and URhGe. Samples were prepared for both polycrystalline and single crystals, which were arc-melted and grown by the Czochralski-pulling method in a tetra-arc furnace, respectively. Annealing is an important process to enhance sample-quality, namely the residual resistivity ratio. We tried to anneal the samples under various temperatures, which were wrapped by the Ta-foil and vacuum-sealed in the quartz ample, together with the solid state electrotransport method in ultra-high vacuum. The highest residual resistivity ratio was 900 for UGe2 and 41 for URhGe. (C) 2003 Published by Elsevier B.V.

    DOI: 10.1016/j.jmmm.2003.12.1083

    Web of Science

    researchmap

  • Unconventional superconductivity and antiferromagnetic spin fluctuations in the heavy fermion compound CeCoIn5: In-115-NQR study under pressure 査読

    M. Yashima, S. Kawasaki, Y. Kawasaki, G. -q. Zheng, Y. Kitaoka, H. Shishido, R. Settai, Y. Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   272   E679 - E681   2004年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report systematic evolution of superconducting (SC) characteristic of heavy-fermion superconductor CeCoIn5 via the nuclear-quadrupole-resonance (NQR) measurement under pressure (P). The temperature dependence of nuclear spin - lattice relaxation rate (1/T-1) below T-C has revealed that once the value of SC energy gap (2 Delta(0)/k(B)T(C)) slightly increases in P&lt;0.45 GPa, with further increasing P, it decreases significantly. By contrast, T-C increases monotonously up to 2.6 K as P increases up to 1 GPa, exhibiting a saturation in P = 1.0-1.5 GPa. (C) 2003 Elsevier B. V. All rights reserved.

    DOI: 10.1016/j.jmmm.2003.11.335

    Web of Science

    researchmap

  • Magnetic anisotropy in the pressure-induced phase of the orthorhombic PrCu2 査読

    T Naka, A Matsushita, T Matsumoto, R Settai, Y Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   272   201 - 202   2004年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    In order to characterize the magnetic state at high pressure, anisotropic susceptibilities, chi(a), chi(b) and chi(c) were measured up to 1.8 GPa in PrCu2, which seems to exhibit a pressure-induced Van Vleck paramagent-to-antiferromagnet transition at 1.2 GPa. It is speculated that the ordered 4f-moments lie in the b-plane in the pressure-induced magnetic state. Remarkable pressure-effects on susceptibility are observed in the b-plane, as indicated in the co-operative Jahn-Teller effect and in the metamagnetism under high field. (C) 2003 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jmmm.2003.11.078

    Web of Science

    researchmap

  • Giant Nernst effect in CeCoIn5 査読

    R Bel, K Behnia, Y Nakajima, K Izawa, Y Matsuda, H Shishido, R Settai, Y Onuki

    PHYSICAL REVIEW LETTERS   92 ( 21 )   2004年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    We present a study of Nernst and Seebeck coefficients of the heavy-fermion superconductor CeCoIn5. Below 18 K, concomitant with a field-dependent Seebeck coefficient, a large sublinear Nernst signal emerges with a magnitude drastically exceeding what is expected for a multiband Fermi-liquid metal. In the mixed state, in contrast with all other superconductors studied before, this signal overwhelms the one associated with the motion of superconducting vortices. The results point to a hitherto unknown source of transverse thermoelectricity in strongly interacting electrons.

    DOI: 10.1103/PhysRevLett.92.217002

    Web of Science

    researchmap

  • Heat-capacity anomalies at Tsc and T* in the ferromagnetic superconductor UGe2 査読

    N. Tateiwa, T. C. Kobayashi, K. Amaya, Y. Haga, R. Settai, Y. Onuki

    Physical Review B - Condensed Matter and Materials Physics   69 ( 18 )   1 - 180513   2004年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The heat-capacity and magnetization measurements under high pressure have been carried out in a ferromagnetic superconductor UGe2. Both measurements were done using a same pressure cell in order to obtain both data for one pressure. Contrary to the heat capacity at ambient pressure, an anomaly is found in the heat capacity at the characteristic temperature T* where the magnetization shows an anomalous enhancement under high pressure where the superconductivity appears. This suggests that a thermodynamic phase transition takes place at T* at least under high pressure slightly below P*c where T* becomes zero. The heat-capacity anomaly associated with the superconducting transition is also investigated, where a clear peak of C/T is observed in a narrow pressure region (ΔP∼0.1 GPa) around P* contrary to the previous results of the resistivity measurement. Present results suggest the importance of the thermodynamic critical point P*c for the appearance of the superconductivity.

    DOI: 10.1103/PhysRevB.69.180513

    Scopus

    researchmap

  • Recent advances in the magnetism and superconductivity of heavy fermion systems 査読

    Y Onuki, R Settai, K Sugiyama, T Takeuchi, TC Kobayashi, Y Haga, E Yamamoto

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 4 )   769 - 787   2004年4月

     詳細を見る

    記述言語:英語   出版者・発行元:PHYSICAL SOC JAPAN  

    We present recent advances in the magnetism and superconductivity of rare earth and uranium compounds. Heavy fermions are formed on the basis of the competition between the RKKY interaction and the Kondo effect in these compounds. The application of pressure to these compounds is useful to control the electronic states in the antiferromagnets CeRh2Si2 and CeRhIn5, and the ferromagnet UGe2. The quadrupole interaction or the quadrupole Kondo effect is found to be responsible for heavy fermions in PrFe4P12. A rich variety of superconducting properties are demonstrated: superconductivity of CeCoIn5 and CeRhIn5 in the vicinity of a quantum critical point, coexistence of ferromagnetism and superconductivity in UGe2, and superconductivity based on the quadrupole fluctuations in PrOs4Sb12, together with the relation between the superconducting transition temperature and the quasi-two dimensionality of the electronic states.

    DOI: 10.1143/JPSJ.73.769

    Web of Science

    researchmap

  • Magnetic structure and the crystal field excitation in heavy-fermion antiferromagnetic super-conductor CePt3Si 査読

    N Metoki, K Kaneko, TD Matsuda, A Galatanu, T Takeuchi, S Hashimoto, T Ueda, R Settai, Y Onuki, N Bernhoeft

    JOURNAL OF PHYSICS-CONDENSED MATTER   16 ( 15 )   L207 - L212   2004年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Neutron scattering experiments have been carried out on the heavy fermion antiferromagnetic (AFM) superconductor CePt3Si with T-N = 2.2 K and T-SC = 0.75 K. We observed clear AFM Bragg reflections with Q(0) = (00 1 /2) below and above T-SC, indicating microscopic coexistence of AFM order and heavy fermion superconductivity. The AFM structure, of two interleaved ferromagnetic sublattices of local Ce 4f moments, has inversion symmetry under simultaneous space-time reversal. However, hybridization with Pt and Si breaks this degeneracy and a combination of these two competing effects may be relevant to an understanding of the simultaneous occurrence of superconductivity and AFM order. The observed magnetic moment 0.16(1) mu(B)/Ce is strongly reduced from the Curie-Weiss effective moment 2.54 mu(B)/Ce. Clear crystal field excitations at 1 and 24 meV were observed. The magnetic susceptibility can be well explained in a level scheme assuming the Gamma(7) ground state, Gamma(6) and Gamma(7) first and second excited states, respectively.

    DOI: 10.1088/0953-8984/16/15/L01

    Web of Science

    researchmap

  • Electronic, magnetic and superconducting properties of quasi-two dimensional compounds Ce2RhIn8 and La2RhIn8 査読

    T Ueda, H Shishido, S Hashimoto, T Okubo, M Yamada, Y Inada, R Settai, H Harima, A Galatanu, E Yamamoto, N Nakamura, K Sugiyama, T Takeuchi, K Kindo, T Namiki, Y Aoki, H Sato, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 3 )   649 - 655   2004年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have measured the electrical resistivity, magnetic Susceptibility, high-field magnetization, specific heat and de Haas-van Alphen (dHvA) oscillation of Ce(2)Rhln(8), together with the dHvA oscillation of La2RhIn8. In La2RhIn8 we detected three kinds of dHvA branches showing cylindrical Fermi surfaces, which are well explained by the result Of FLAPW energy band calculations. The corresponding two dHvA branches were detected in Ce2RhIn8, indicating that the topology of the Fermi surface in Ce2RhIn8 is approximately the same as that of LaRhIn8. The magnetic susceptibility and magnetization of Ce2RhIn8 were analyzed on the basis of the crystalline electric field scheme of localized-4f energy levels. Pressure-induced superconductivity was confirmed above 1.2GPa from the resistivity and ac-susceptibility measurements.

    DOI: 10.1143/JPSJ.73.649

    Web of Science

    researchmap

  • First observation of the de Haas-van Alphen effect in NpNiGa5 査読

    D Aoki, E Yamamoto, Y Homma, Y Shiokawa, A Nakamura, Y Haga, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 3 )   519 - 522   2004年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in observing the de Haas-van Alphen (dHvA) oscillations in NpNiGa5 Single crystals, which were grown by the Ga-flux method. This is the first dHvA observation in transuranium compounds. The cyclotron effective masses were moderately enhanced, ranging from 1.8 to 4.9m(0) (m(0): rest mass of an electron). From an intensive change of the dHvA amplitude at 80-90kOe and the temperature dependence of the electrical resistivity, NpNiGa5 is most likely an antiferromagnet with a Neel temperature, T-N = 30 K.

    DOI: 10.1143/JPSJ.73.519

    Web of Science

    researchmap

  • Pressure-induced superconductivity in ferromagnetic UIr without inversion symmetry 査読

    T Akazawa, H Hidaka, T Fujiwara, TC Kobayashi, E Yamamoto, Y Haga, R Settai, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   16 ( 4 )   L29 - L32   2004年2月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We report the discovery of pressure-induced superconductivity in ferromagnetic UIr, which lacks inversion symmetry in the crystal structure. The Curie temperature T-CI = 46 K at ambient pressure decreases with increasing pressure, reaching a value of 11 K at 1.5 GPa. It presumably decreases further up to about P-cl = 1.7 GPa. The ferromagnetic region named 'Fl' exists up to P-cl. A second magnetic phase named 'F2' with a low ferromagnetic moment appears in the pressure range frorn 1.9 to 2.4 GPa. In the 'F2' phase, the magnetic transition temperature T-C2 decreases with pressure, from 18 K at 1.9 GPa to approximately zero at P-C2 = 2.6-2.7 GPa. In this critical pressure region, superconductivity appears below T-sc = 0.14 K.

    DOI: 10.1088/0953-8984/16/4/L02

    Web of Science

    researchmap

  • Normal-state hall angle and magnetoresistance in Quasi-2D heavy fermion CeCoIn5 near a quantum critical point 査読

    Y Nakajima, K Izawa, Y Matsuda, S Uji, T Terashima, H Shishido, R Settai, Y Onuki, H Kontani

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 1 )   5 - 8   2004年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The normal-state Hall effect and magnetoresisitance (MR) have been measured in the quasi two dimensional (2D) heavy fermion superconductor CeCoIn5. In the non-Fermi liquid region where the reistivity rho(xx) exhibits an almost perfect T-linear dependence, the Hall angle varies as cot theta(H) proportional to T-2 and MR displays a strong violation of Kohler's rule. We demonstrate a novel relation between the MR and the Hall conductivity, Deltarho(xx)/rho(xx) proportional to (sigma(xy)rho(xx))(2). These results bear a striking resemblance to the normal-state properties of high-T-c cuprates, indicating universal transport properties in the presence of quasi-2D anti ferromagnetic fluctuations near a quantum critical point.

    DOI: 10.1143/JPSJ.73.5

    Web of Science

    researchmap

  • Field-angle dependence of the zero-energy density of states in the unconventional heavy-fermion superconductor CeCoIn5 査読

    H Aoki, T Sakakibara, H Shishido, R Settai, Y Onuki, P Miranovic, K Machida

    JOURNAL OF PHYSICS-CONDENSED MATTER   16 ( 3 )   L13 - L19   2004年1月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    Field-angle-dependent specific heat measurements have been made on the heavy-fermion superconductor CeCoIn5 down to similar to0.29 K, in a magnetic field rotating in the tetragonal c-plane. A clear fourfold angular oscillation is observed in the specific heat with the minima (maxima) occurring along the [100] ([110]) directions. Oscillation persists down to low fields H much less than H-c2, thus directly proving the existence of gap nodes. The results indicate that the superconducting gap symmetry is most probably of d(xy) type.

    DOI: 10.1088/0953-8984/16/3/L02

    Web of Science

    researchmap

  • 超ウラン化合物で初めて決定されたNpCoGa5の円柱状フェルミ面 査読

    青木大, 本間佳哉, 塩川佳伸, 山本悦嗣, 芳賀芳範, 中村彰夫, 摂待力生, 竹内徹也, 大貫惇睦

    固体物理   39 ( 8 )   537 - 544   2004年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Unique Fermi surfaces with quasi-one-dimensional, character in CeRh3B2 and LaRh3B2 査読

    T Okubo, M Yamada, A Thamizhavel, S Kirita, Y Inada, R Settai, H Harima, K Takegahara, A Galatanu, E Yamamoto, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   15 ( 46 )   L721 - L727   2003年11月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We have carried out de Haas-van Alphen (dHvA) experiments on a ferromagnet CeRh3B2 with an extremely high Curie temperature T-C similar or equal to 120 K and a non-4f reference compound LaRh3B2. The dHvA data of LaRh3B2 are well explained by the results of energy band calculations. The topology of the Fermi surfaces in CeRh3B2 is found to be very similar to that of LaRh3B2, possessing wavy but flat Fermi surfaces in the basal plane. Observation of a quasi-one-dimensional electronic state is the first such case in a rare earth compound.

    DOI: 10.1088/0953-8984/15/46/L02

    Web of Science

    researchmap

  • Magnetic properties of CeNiGe2 査読

    Y Okada, Y Inada, A Galatanu, E Yamamoto, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   72 ( 10 )   2692 - 2693   2003年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    DOI: 10.1143/JPSJ.72.2692

    Web of Science

    researchmap

  • Low temperature magnetic properties of CeTBi2 (T : Ni, Cu and Ag) single crystals 査読

    A Thamizhavel, A Galatanu, E Yamamoto, T Okubo, M Yamada, K Tabata, TC Kobayashi, N Nakamura, K Sugiyama, K Kindo, T Takeuchi, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   72 ( 10 )   2632 - 2639   2003年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    A series of the ternary compounds CeTBi2 (T: Ni, Cu and Ag) have been grown in the single crystalline form by means of the flux method. These compounds crystallize in the tetragonal crystal structure. Measurements of the electrical resistivity, magnetic susceptibility, magnetization, low temperature specific heat and de Haas-van Alphen effect are reported. These compounds order antiferromagnetically with an easy-axis of magnetization along the [001] direction(c-axis). The electrical resistivity and magnetic susceptibility are highly anisotropic, reflecting the quasi-two dimensional crystal structure.

    DOI: 10.1143/JPSJ.72.2632

    Web of Science

    researchmap

  • Magnetic properties and a change of the electrical resistivity under pressure in CePtGe2 査読

    S Kirita, A Thamizhavel, T Takeuchi, K Tabata, TC Kobayashi, A Galatanu, E Yamamoto, R Settai, S Ramakrishnan, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   72 ( 9 )   2338 - 2343   2003年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have succeeded in growing a single crystal of CePtGe2 with the orthorhombic crystal structure by the Bi-flux method. In order to investigate the anisotropic properties, the magnetic susceptibility, magnetization and electrical resistivity measurements have been performed along the principal axes. From these measurements, it is found that CePtGe2 orders ferromagnetically below T-C = 5.1 K, and the magnetic easy-axis corresponds to the a-axis. The anisotropic properties have been analyzed on the basis of the crystalline electric field model. We have also studied the pressure effect on the ferromagnetic ordering, and T-C is found to increase with increasing pressure. However, T-C smears out around 3.5 GPa and a new phase appears at higher pressures, where the transition temperature of the new phase also increases with increasing pressure.

    DOI: 10.1143/JPSJ.72.2338

    Web of Science

    researchmap

  • Anisotropic spin fluctuations in heavy-fermion superconductor CeCoIn5: In-NQR and Co-NMR studies 査読

    Y Kawasaki, S Kawasaki, M Yashima, T Mito, GQ Zheng, Y Kitaoka, H Shishido, R Settai, Y Haga, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   72 ( 9 )   2308 - 2311   2003年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report In-NQR and Co-NMR experiments of CeCoIn5 that undergoes a superconducting transition with a record high T-c = 2.3 K to date among heavy-fermion superconductors. At zero magnetic field, an anomalous temperature (T) dependence of nuclear spin-lattice relaxation rate 1/T-1 of In-115 is explained by the relation 1/T-1 proportional to T (.) chi(Q)(T)(3/4) based on the anisotropic spin-fluctuations model in case of the proximity to an antiferromagnetic (AFM) quantum critical point (QCP). The novel behavior of 1/T-1 similar to T-1/4 over a wide T range of T-c &lt; T &lt; 40 K arises because the staggered susceptibility almost follows the Curie law chi(Q)(T) proportional to 1/(T + theta) with theta = 0.6 K and hence 1/T-1 proportional to T/(T + 0.6)(3/4) similar to T-1/4 for theta &lt; T. We highlight that the behavior 1/T-1 similar to T-1/4 is due to the proximity to the anisotropic AFM QCP relevant with. its layered structure, and is not associated with the AFM QCP for isotropic 3D systems. We have also found that the AFM spin fluctuations in CeCoIn5 are suppressed by small magnetic field so that theta = 0.6 K at H = 0 increases to theta = 2.5 K at H = 1.1 T, reinforcing that CeCoIn5 is closely located at the QCP.

    DOI: 10.1143/JPSJ.72.2308

    Web of Science

    researchmap

  • A de Haas-van Alphen experiment under pressure on CeCoIn5: deviation from the quantum critical region 査読

    H Shishido, T Ueda, S Hashimoto, T Kubol, R Settai, H Harima, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   15 ( 32 )   L499 - L504   2003年8月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We have carried out a de Haas-van Alphen experiment under pressure on a heavy-fermion superconductor, CeCoIn5. Large cyclotron masses of 15 m(0) (m(0:) the rest mass of an electron) in a nearly cylindrical Fermi surface called alpha(i) (i = 1, 2, 3) and 60 m(0) in a similar cylindrical Fermi surface called beta(2) at ambient pressure are found to be strongly reduced to 7 and 40 m(0), respectively, at 3 GPa. Correspondingly, the field-dependent cyclotron mass at ambient pressure becomes almost independent of the field at high pressures. These results indicate that CeCoIn5, which is in the vicinity of the quantum critical region at ambient pressure, is changed into a usual heavy-fermion state under high pressures of about 3 GPa.

    DOI: 10.1088/0953-8984/15/32/101

    Web of Science

    researchmap

  • Anisotropic electrical and magnetic properties of CeTSb2 (T=Cu, Au, and Ni) single crystals 査読

    A Thamizhavel, T Takeuchi, T Okubo, M Yamada, R Asai, S Kirita, A Galatanu, E Yamamoto, T Ebihara, Y Inada, R Settai, Y Onuki

    PHYSICAL REVIEW B   68 ( 5 )   2003年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    In order to understand the anisotropic magnetic and electrical properties of ternary compounds CeTSb2 (T=Cu, Au, Ni) with the tetragonal structure, we have grown single crystals of this series by the self-flux method and measured the electrical resistivity, magnetic susceptibility, magnetization, and specific heat. CeCuSb2 and CeAuSb2 are found to order antiferromagnetically with Neel temperatures of 6.9 K and 5.0 K, respectively, while CeNiSb2 is a ferromagnet with a Curie temperature of 6.0 K with an easy axis of magnetization oriented along the [100] direction. The magnetic property of CeCuSb2 shows a very small anisotropy, whereas the electrical resistivity is highly anisotropic between Jparallel to [100] and [001]. In contrast, CeAuSb2 and CeNiSb2 show a strong anisotropy both in the magnetic and electrical measurements, although the magnetic easy axis is interchanged with respect to each other. The anisotropy in the magnetic properties has been explained on the basis of a crystalline electric-field model.

    DOI: 10.1103/PhysRevB.68.054427

    Web of Science

    researchmap

  • An anomalously huge resistivity peak under pressure in CeRhGe 査読

    R Asai, A Thamizhavel, H Shishido, T Ueda, Y Inada, R Settai, C Kobayashi, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   15 ( 29 )   L463 - L468   2003年7月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We have measured the electrical resistivity under pressure up to 2 GPa for an antiferromagnet, CeRhGe. The resistivity at ambient pressure decreases monotonically below a Neel temperature T-N = 10 K. With increasing pressure P, the resistivity has a peak around 10 K, which is anomalously enhanced up to 1.2 GPa. With further increasing pressure, the resistivity peak is diminished; the Neel temperature becomes zero at a critical pressure P-c = 9 GPa. The A-value of the resistivity rho in the Fermi liquid relation rho = rho(0) +AT(2) is also found to increase with increasing pressure and has a maximum at Pc which corresponds to the value for the heavy-fermion superconductor CeCu2Si2.

    DOI: 10.1088/0953-8984/15/29/102

    Web of Science

    researchmap

  • Pressure-induced magnetic transition in the Van Vleck paramagnet PrCu2 査読

    T Naka, J Tang, JH Ye, A Matsushita, T Matsumoto, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   72 ( 7 )   1758 - 1762   2003年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report the pressure effects on lattice constants, magnetic susceptibility, specific heat and electrical resistivity in the orthorhombic PrCu2. Anisotropic compression is realized to be kappa(a) approximate to kappa(c) &lt; kappa(b) even under hydrostatic pressure. Above 1.2 GPa, susceptibility shows a remarkable maximum at T-max. This fact implies that the pressure-induced magnetic ordering occurs above 1.2 GPa. Also the results of specific heat and electrical resistivity reveal the anomaly at P = 1.2 GPa to be due to an antiferromagnetic ordering. The temperature-pressure phase diagram is presented up to 2 GPa.

    DOI: 10.1143/JPSJ.72.1758

    Web of Science

    researchmap

  • Exotic behaviours in the Pr-based filled skutterudites 査読

    H Sato, H Sugawara, T Namiki, Saha, SR, S Osaki, TD Matsuda, Y Aoki, Y Inada, H Shishido, R Settai, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   15 ( 28 )   S2063 - S2070   2003年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    The exotic features of the Pr-based filled skutterudites are reviewed based on the electronic transport properties, specific heat and de Haas-van Alphen experiments, putting the emphasis on PrFe4P12 and PrOs4Sb12. As references, the experiments on the related La- and Ce-filled skutterudites are also examined and discussed. Compared to their La reference compounds, the Fermi surface is very similar in PrOs4Sb12, suggesting the well localized character of 4f electrons, while it looks largely different in PrFe4P12. For the cyclotron effective mass, both PrFe4P12 and PrOS4Sb12 exhibit a strong enhancement, in reasonable agreement with the large specific heat coefficient.

    DOI: 10.1088/0953-8984/15/28/326

    Web of Science

    researchmap

  • The de Haas-van Alphen effect in URu2Si2 under pressure 査読

    M Nakashima, H Ohkuni, Y Inada, R Settai, Y Haga, E Yamamoto, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   15 ( 28 )   S2011 - S2014   2003年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We carried out a de Haas-van Alphen (dHvA) experiment under pressure on a heavy-fermion superconductor, URu2Si2. The dHvA frequency, which corresponds to a nearly spherical Fermi surface, increases slightly with increasing pressure, while the corresponding cyclotron mass decreases considerably. Neither the dHvA frequency nor the cyclotron mass exhibit any abrupt change at the critical pressure of 1.5 GPa. The present result is thus inconsistent with a recent phase-separation proposal.

    DOI: 10.1088/0953-8984/15/28/316

    Web of Science

    researchmap

  • The high-pressure effect of an electronic state in uranium compounds: UPtGa5 and UN 査読

    M Nakashima, Y Haga, E Yamamoto, Y Tokiwa, M Hedo, Y Uwatoko, R Settai, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   15 ( 28 )   S2007 - S2010   2003年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We studied the electronic states of two antiferromagnets, UPtGa5 and UN, by measuring the electrical resistivity under pressure. When pressure P is applied, the Neel temperature T-N decreases, becoming zero at P-c = 8.0 GPa for UPtGa5 and P-c = 3.5 GPa for UN.

    DOI: 10.1088/0953-8984/15/28/315

    Web of Science

    researchmap

  • High-quality single crystal growth and the Fermi surface property of uranium and cerium compounds 査読

    Y Onuki, Y Haga, E Yamamoto, Y Inada, R Settai, H Yamagami, H Harima

    JOURNAL OF PHYSICS-CONDENSED MATTER   15 ( 28 )   S1903 - S1909   2003年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We present descriptions of the single crystal growth of uranium and cerium compounds via the Czochralski-pulling, self-flux and vapour transport methods. We also report the results of de Haas-van Alphen experiments and energy band calculations for a Hill-plot rule of UX3 (X: Si, Ge, Sn and Pb), heavy fermion systems of UPt3 and UPd2Al3, quasi-two-dimensional electronic states of UPtGa5, UX2 (X: Bi, Sb, As, P) and CeCoIn5, characteristic semimetals of UC and CeAgSb2, and quantum critical phenomena in UGe2 and CeRh2Si2.

    DOI: 10.1088/0953-8984/15/28/301

    Web of Science

    researchmap

  • Magnetism and high-field magnetization of RCu2 査読

    K Sugiyama, T Yamamoto, N Nakamura, K Kindo, R Settai, Y Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   262 ( 3 )   389 - 398   2003年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We measured the magnetization of CeCu2, PrCu2, TbCu2, DyCu2 and TmCu2 in high magnetic fields up to 40 T and in a wide temperature range from 1.3 to 150 K, and observed a metamagnetic transition with a large hysteresis. The present metamagnetic transition occurs in the ac-plane of the orthorhombic crystal structure, which was analysed on the basis of the quadrupole moment O-2(2). (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0304-8853(03)00069-6

    Web of Science

    researchmap

  • De Haas-Van Alphen experiments under extreme conditions of low temperature, high field and high pressure, for high-quality cerium and uranium compounds 査読

    R Settai, S Araki, H Shishido, Y Inada, Y Haga, E Yamamoto, TC Kobayashi, N Tateiwa, Y Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   262 ( 3 )   399 - 406   2003年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    When pressure is applied to cerium and uranium compounds, the magnetic ordering temperature is suppressed and becomes zero at a critical pressure P-c. Around P-c, non-Fermi liquid and/or superconductivity are observed. We clarified a change of the electronic state via a de Haas-van Alphen (dHvA) experiment when pressure crosses P-c. The dHvA experiment under pressure was done for the antiferromagnets CeRh2Si2 and CeRhIn5, and for a ferromagnet UGe2. We found an abrupt change of the Fermi surface for CeRh2Si2 and UGe2 when crossing P-c, indicating a first-order like phase transition. For CeRhIn5, the topology of the Fermi surface was unchanged, but the cyclotron mass increased steeply above 1.6 Gpa, where superconductivity sets in. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0304-8853(03)00070-2

    Web of Science

    researchmap

  • De Haas-van Alphen effect of CeRhIn5 under pressure 査読

    H Shishido, R Settai, S Araki, T Ueda, Y Inada, H Harima, Y Onuki

    PHYSICA B-CONDENSED MATTER   329   526 - 527   2003年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have studied the de Haas-van Alphen (dHvA) effect under pressure for an antiferromagnet CeRhIn5, where the antiferromagnetic state is changed into the superconducting state at higher pressures than 1.6 GPa. It is clarified from the present dHvA experiment that the topology of the Fermi surface is unchanged up to 2.1 GPa but the cyclotron mass increases strongly above 1.6 GPa. Superconductivity is found to be realized in this heavy fermion state. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(02)02366-9

    Web of Science

    researchmap

  • A heat capacity anomaly of the superconducting transition in a ferromagnetic superconductor UGe2 査読

    N Tateiwa, TC Kobayashi, K Amaya, Y Haga, R Settai, Y Onuki

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   388   527 - 528   2003年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We performed the heat capacity, C(T), measurement under high pressure on a ferromagnetic superconductor UGe2, in order to study the pressure dependence of the anomaly in C(T) associated with the superconducting transition. A clear peak appears only around a critical pressure P-c(*) where an another transition temperature T* becomes 0 K. This result suggests that a bulk superconducting phase exists in the narrower pressure region around P-c(*), than those clarified by previous studies. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4534(02)02650-3

    Web of Science

    researchmap

  • Unconventional superconductivity in CeIn3: In-115-NQR study under pressure 査読

    S Kawasaki, Y Kawasaki, T Mito, GQ Zheng, Y Kitaoka, S Araki, R Settai, Y Onuki

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   388   541 - 542   2003年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report evidences for bulk nature and unconventional superconductivity in CeIn3 at P = 2.65 GPa revealed by the measurements of nuclear-spin-lattice-relaxation time (T-1) and ac-susceptibility (ac-chi). Both the measurements of ac-chi and T, have pointed to a superconducting transition at T = 95 mK, which is very much lower than an onset temperature T-onset = 0.15 K at zero resistance. The temperature dependence of 1/T-1 shows no coherence peak just below T-c, indicative of an unconventional nature for the superconductivity. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4534(02)02732-6

    Web of Science

    researchmap

  • Gap structure and anomalous superconducting state of quasi-2D heavy-fermion CeCoIn5 査読

    K Izawa, H Yamaguchi, Y Matsuda, H Shishido, R Settai, Y Onuki

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   388   537 - 538   2003年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    To specify the direction of the nodes in the superconducting gap, we measured the thermal conductivity K of quasi-2D heavy-fermion CeCoIn5 in a magnetic field rotating within the 2D planes. A clear fourfold symmetry Of K which is characteristic of a superconducting gap with nodes along the (+/-pi, +/-pi)-directions is resolved. The thermal conductivity also reveals a first order phase transition at H-c2. The results indicate that the symmetry most likely belongs to d(x2-y2), implying that the anisotropic antiferromagnetic fluctuation is relevant to the superconductivity. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4534(02)02730-2

    Web of Science

    researchmap

  • De Haas-van Alphen effect under pressure in URu2Si2 査読

    M Nakashima, S Ikeda, T Okubo, Y Inada, R Settai, H Ohkuni, E Yamamoto, Y Haga, Y Onuki

    PHYSICA B-CONDENSED MATTER   329   566 - 567   2003年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We carried out the de Haas-van Alphen experiment under pressure for a heavy fermion antiferromagnet URu2Si2. The detected cyclotron mass for a nearly spherical Fermi surface under pressure changes considerably, reflecting a change of the magnetic moment. The present result is, however, inconsistent with the recent phase separated proposal. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(02)02443-2

    Web of Science

    researchmap

  • Magnetic and Fermi surface properties of UTGa5 (T : Fe, Co and Pt) 査読

    S Ikeda, Y Tokiwa, T Okubo, M Yamada, TD Matsuda, Y Inada, R Settai, E Yamamoto, Y Haga, Y Onuki

    PHYSICA B-CONDENSED MATTER   329   610 - 611   2003年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We succeeded in growing high-quality single crystals of UTGa5 (T: Fe, Co and Pt) by the self-flux method, and measured the de Haas-van Alphen effect. With increasing the number of 3d-electrons, from Fe to Pt, the Fermi surface is found to change systematically, indicating cylindrical Fermi surfaces in UFeGa5 and UPtGa5. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(02)02496-1

    Web of Science

    researchmap

  • de Haas-van Alphen effect in LaRu4P12 査読

    Saha, SR, H Sugawara, R Sakai, Y Aoki, H Sato, Y Inada, H Shishido, R Settai, U Onuki, H Harima

    PHYSICA B-CONDENSED MATTER   328 ( 1-2 )   68 - 70   2003年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report the first successful observation of the de Haas van Alphen effect in the filled skutterudite LaRu4P12. Observed Fermi surfaces (FSs) are close to those expected from the band calculation. The effective mass m(c)* is roughly twice compared to the calculated band mass. Assuming the similarity of FS between LaRu4P12 and PrRu4P12, the FS nesting with q = (1, 0, 0) as a possible origin of the M-I transition in PrRu4R12 is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(02)01811-2

    Web of Science

    researchmap

  • De Haas-van Alphen experiments in the quantum critical region of cerium and uranium compounds 査読

    Y Onuki, R Settai, S Araki, M Nakashima, H Ohkuni, H Shishido, A Thamizhavel, Y Inada, Y Haga, E Yamamoto, TC Kobayashi

    ACTA PHYSICA POLONICA B   34 ( 2 )   667 - 678   2003年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAGIELLONIAN UNIV PRESS  

    When pressure is applied to the cerium and uranium compounds, their magnetic ordering temperatures are suppressed and become zero at a critical pressure P-c. Around P-c non-Fermi liquid and/or superconductivity are observed. We clarified a change of the electronic state via the de Haas-van Alphen (dHvA) experiment when pressure crosses P-c. The dHvA experiment under pressure was done for antiferromagnets CeRh2Si2, CeRhIn5 and URu2Si2, and a ferromagnet UGe2. We find an abrupt change of the Fermi surface for CeRh2Si2 and UGe2 when crossing P-c, indicating a first-order like phase transition. For CeRhIn5 and URu2Si2, a change of the cyclotron mass is clearly observed.

    Web of Science

    researchmap

  • De Haas-Van Alphen effect in heavy fermion superconductor PrOs4Sb12 査読

    H Sugawara, S Osaki, Saha, SR, Y Aoki, H Sato, Y Inada, H Shishido, R Settai, Y Onuki

    ACTA PHYSICA POLONICA B   34 ( 2 )   1125 - 1128   2003年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAGIELLONIAN UNIV PRESS  

    We have succeeded in observing the de Haas-van Alphen (dHvA) effect in PrOS4Sb12. The Fermi surface topology is similar to the reference compound LaOS4Sb12, indicating the localized character of 4f-electrons. The cyclotron effective mass, enhanced by about four times compared with LaOs4Sb12, is a direct evidence of the strong electron correlation in this compound.

    Web of Science

    researchmap

  • Huge residual resistivity in the quantum critical region of CeAgSb2 査読

    M Nakashima, S Kirita, R Asai, TC Kobayashi, T Okubo, M Yamada, A Thamizhavel, Y Inada, R Settai, A Galatanu, E Yamamoto, T Ebihara, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   15 ( 4 )   L111 - L117   2003年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We have studied the effect of pressure on the electrical resistivity of a high-quality single crystal CeAgSb2 which has a small net ferromagnetic moment of 0.4 mu(B)/Ce. The magnetic ordering temperature. T-ord = 9.7 K decreases with increasing pressure p and disappears at a critical pressure p(c) similar or equal to 3.3 GPa. The residual resistivity, which is close to zero up to 3 GPa, increases steeply above 3 GPa, reaching 55 muOmega cm at p(c). A huge residual resistivity is found to appear when the magnetic order disappears.

    DOI: 10.1088/0953-8984/15/4/101

    Web of Science

    researchmap

  • de Haas-van Alphen experiments under pressure in UGe2 査読

    R Settai, M Nakashima, H Shishido, Y Haga, H Yamagami, Y Onuki

    ACTA PHYSICA POLONICA B   34 ( 2 )   725 - 728   2003年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS  

    We have studied the electronic state in UGe2 via the de Haas-van Alphen effect under pressure. The cyclotron masses are determined in the strongly polarized phase and in the paramagnetic phase for magnetic field along the c-axis and the results are compared with those along a- and b-axes.

    Web of Science

    researchmap

  • Superconductivity in CeRh2Si2 under pressure 査読

    S Araki, M Nakashima, R Settai, TC Kobayashi, Y Onuki

    ACTA PHYSICA POLONICA B   34 ( 2 )   439 - 442   2003年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS  

    We have studied the pressure-induced superconductivity in an antiferromagnet CeRh2Si2 by measuring the electrical resistivity for a high-quality single crystal. The superconducting resistivity drop was observed around P-c similar or equal to 1.06 GPa, at which the Neel temperature becomes zero(1) namely in a pressure region from 0.97 to 1.20 GPa. The zero resistivity appears below 0.4 K between 1.03 to 1.08 GPa. The resistivity at low temperatures follows the Fermi liquid AT(2) relation in the whole pressure region, even at P-c. The A value becomes a maximum around P-c.

    Web of Science

    researchmap

  • First-order superconducting transition at the upper critical field in CeCoIn5 studied by DC magnetization measurement 査読

    T Sakakibara, T Tayama, A Harita, Y Haga, H Shishido, R Settai, Y Onuki

    ACTA PHYSICA POLONICA B   34 ( 2 )   467 - 470   2003年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS  

    DC magnetization process of a high-quality single crystal of CeCoIn5 has been measured at low temperatures down to 50mK. A sharp magnetization jump with a small hysteresis is observed at the upper critical field H-c2 for both a and c directions, indicating the transition to the normal state to be of first-order. Although the results might suggest a strong Pauli paramagnetic effect, no Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase is observed.

    Web of Science

    researchmap

  • A heat capacity anomaly at T* in a ferromagnetic superconductor UGe2 査読

    N Tateiwa, TC Kobayashi, K Amaya, Y Haga, R Settai, Y Onuki

    ACTA PHYSICA POLONICA B   34 ( 2 )   515 - 518   2003年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS  

    We performed the heat capacity, C(T), measurement under high pressure for a ferromagnetic superconductor UGe2. At 1.15 GPa, we found a peak in C/T at a characteristic temperature, T-* = 6 K where the magnetization showed anomalous increase. At 1.28 GPa, above the critical pressure P-c(*) where T-* becomes 0 K, C/T does not show notable anomaly at zero magnetic field, but the application of the external field above 2.5 T induces the peak again at T-* &gt; 0 K. It corresponds to the induction of T-* by the magnetic field. Our experimental result suggests that a second order phase transition takes place at T-* and thus a disappearance of the phase transition at T-* is of second order.

    Web of Science

    researchmap

  • Single crystal growth and annealing temperature of ferromagnetic URhGe 査読

    E Yamamoto, Y Haga, TD Matsuda, Y Inada, R Settai, Y Tokiwa, Y Onuki

    ACTA PHYSICA POLONICA B   34 ( 2 )   1059 - 1062   2003年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAGIELLONIAN UNIV PRESS  

    We searched for an experimental condition of crystal growth for a ferromagnetic superconductor URhGe. Samples were prepared for both poly-crystalline and single crystals, which were arc-melted and grown by the Czochralski-pulling method in a tetra-arc furnace, respectively. Annealing is an important process in order to increase sample-quality, namely the residual resistivity ratio. We tried to anneal the samples under various temperatures, which were wrapped by the Ta-foil and vacuum-sealed in the quartz ample, together with the solid state electrotransport (SSE) method in ultra-high vacuum.

    Web of Science

    researchmap

  • Magnetic Properties of CeRhIn5 under Pressure Probed by 115In-NQR

    S. Kawasaki, T. Mito, G.-q. Zheng, Y. Kawasaki, Y. Kitaoka, D. Aoki, Y. Haga, R. Settai, Y. Onuki

    Acta Phys. Polonica B   2003年

     詳細を見る

  • Fermi surface of the heavy-fermion superconductor PrOs4Sb12 査読

    H Sugawara, S Osaki, Saha, SR, Y Aoki, H Sato, Y Inada, H Shishido, R Settai, Y Onuki, H Harima, K Oikawa

    PHYSICAL REVIEW B   66 ( 22 )   2002年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We have investigated the de Haas-van Alphen effect in the Pr-based heavy-fermion superconductor PrOs4Sb12. The topology of Fermi surface is close to the reference compound LaOs4Sb12 and well explained by the band-structure calculation based on the FLAPW (full potential linearized augmented-plane-wave)-LDA (local-density approximation) +U method, where the 4f electrons are localized. We have confirmed a highly enhanced cyclotron effective mass (2.4-7.6)m(0), which is apparently large compared to the usual Pr-based compounds.

    DOI: 10.1103/PhysRevB.66.220504

    Web of Science

    researchmap

  • An unusual hollow cylindrical Fermi surface of a quasi-two-dimensional compound CeAgSb2 査読

    Y Inada, A Thamizhavel, H Yamagami, T Takeuchi, Y Sawai, S Ikeda, H Shishido, T Okubo, M Yamada, K Sugiyama, N Nakamura, T Yamamoto, K Kindo, T Ebihara, A Galatanu, E Yamamoto, R Settai, Y Onuki

    PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES   82 ( 18 )   1867 - 1892   2002年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TAYLOR & FRANCIS LTD  

    We have carried out the de Haas-van Alphen (dHvA) experiment, together with electrical resistivity, magnetic susceptibility, magnetization and specific heat experiments on a high-quality single-crystal CcAgSb(2), which has a small net ferromagnetic moment of 0.4 mu(B) per Cc atom. The bulk magnetic properties are well explained by the crystalline electric field scheme. On the other hand, large dHvA frequencies of 10(8) Oe, which correspond to cylindrical Fermi surfaces, were detected by the dHvA measurement for the magnetic field along the tetragonal [001] direction, indicating the quasi-two-dimensional electronic structure. The dHvA branches of CeAgSb2 are highly different from those with small dHvA frequencies of 10(7) Oe for the reference compounds LaAgSb2 and YAgSb2 which exhibit a semimetallic character. The dHvA results have been compared with the results of the energy band calculations. It was concluded that the 4f electron is mainly localized and that the Fermi surface of CeAgSb2 is similar to that of LaAgSb2, but it is slightly enlarged so as to form the large orbits along a hollow cylindrical Fermi surface.

    DOI: 10.1080/1364281021000036823

    Web of Science

    researchmap

  • Pressure-induced superconductivity in a ferromagnet, UGe2: resistivity measurements in a magnetic field 査読

    TC Kobayashi, K Hanazono, N Tateiwa, K Amaya, Y Haga, R Settai, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   14 ( 44 )   10779 - 10782   2002年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Electrical resistivity measurements in a magnetic field are carried out on UGe2 which exhibits pressure-induced superconductivity. The superconductivity is observed from 1.06 to 1.44 GPa. In the temperature and field dependences of the resistivity at P &gt; PC where the ferromagnetic ordering disappears, it is observed that the application of an external field along the a-axis increases the coefficient A of the Fermi-liquid behaviour (alphaAT(2)) abruptly-corresponding to the metamagnetic transition. The characteristic enhancement of H-C2 is reconfirmed for H parallel to a-axis. The upper critical field of H-C2 is anisotropic: H-C2(T) exhibits positive curvature for H parallel to b-axis and H parallel to c-axis.

    DOI: 10.1088/0953-8984/14/44/376

    Web of Science

    researchmap

  • Exotic heavy-fermion state in the filled skutterudite PrFe4P12 uncovered by the de Haas-van Alphen effect

    H. Sugawara, T. D. Matsuda, K. Abe, Y. Aoki, H. Sato, S. Nojiri, Y. Inada, R. Settai, Y. Onuki, Y. Onuki

    Physical Review B - Condensed Matter and Materials Physics   66   1344111 - 1344115   2002年10月

     詳細を見る

    We report the de Haas-van Alphen (dHvA) experiment on the filled skutterudite PrFe4P12 exhibiting apparent Kondo-like behaviors in the transport and thermal properties. We have found enormously enhanced cyclotron effective mass mc* = 81 m0 in the high field phase, which indicates that PrFe4P12 is the first Pr compound in which really heavy mass has been unambiguously confirmed. Also in the low field nonmagnetic ordered phase (LOP), we observed the dHvA branch with mc* = 10 m0 that is quite heavy taking into account its small Fermi surface volume (0.15% of the Brillouin zone size). The insensitivity of mass in LOP against the magnetic field suggests that the quadrupolar interaction plays a main role both in the mass renormalization and the LOP formation.

    Scopus

    researchmap

  • Exotic heavy-fermion state in the filled skutterudite PrFe4P12 uncovered by the de Haas-van Alphen effect 査読

    H Sugawara, TD Matsuda, K Abe, Y Aoki, H Sato, S Nojiri, Y Inada, R Settai, Y Onuki

    PHYSICAL REVIEW B   66 ( 13 )   2002年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report the de Haas-van Alphen (dHvA) experiment on the filled skutterudite PrFe4P12 exhibiting apparent Kondo-like behaviors in the transport and thermal properties. We have found enormously enhanced cyclotron effective mass m(c)(*)=81 m(0) in the high field phase, which indicates that PrFe4P12 is the first Pr compound in which really heavy mass has been unambiguously confirmed. Also in the low field nonmagnetic ordered phase (LOP), we observed the dHvA branch with m(c)(*)=10 m(0) that is quite heavy taking into account its small Fermi surface volume (0.15% of the Brillouin zone size). The insensitivity of mass in LOP against the magnetic field suggests that the quadrupolar interaction plays a main role both in the mass renormalization and the LOP formation.

    DOI: 10.1103/PhysRevB.66.134411

    Web of Science

    researchmap

  • In-115-NQR evidence for unconventional superconductivity in CeIn3 under pressure 査読

    S Kawasaki, T Mito, Y Kawasaki, GQ Zheng, Y Kitaoka, H Shishido, S Araki, R Settai, Y Onuki

    PHYSICAL REVIEW B   66 ( 5 )   2002年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report evidence for unconventional superconductivity in CeIn3 at a pressure P=2.65 GPa above the critical pressure (P(c)similar to2.5 GPa) revealed by measurements of the nuclear-spin-lattice-relaxation time (T-1) and ac susceptibility (ac-chi). Both measurements of T-1 and ac-chi have pointed to a superconducting transition at T-c=95 mK, which is much lower than the onset temperature T-onset=0.15 K at zero resistance. The temperature dependence of 1/T-1 shows no coherence peak just below T-c, indicative of an unconventional nature for the superconductivity induced in CeIn3.

    DOI: 10.1103/PhysRevB.66.054521

    Web of Science

    researchmap

  • Magnetization study of the heavy fermion superconductor CeCoIn5 査読

    T Tayama, A Harita, T Sakakibara, Y Haga, H Shishido, R Settai, Y Onuki

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   63 ( 6-8 )   1155 - 1158   2002年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We report the high-resolution dc magnetization measurements in the heavy fermion superconductor CeCoIn5 at very low temperatures down to 50 mK in fields up to 125 kOe. A clear magnetization jump is observed at the upper critical field H,2 for both Hparallel toa and c axes in the isothermal magnetization curve below 0.7 K, indicating the existence of a first-order phase transition at H-c2, It is likely that the first-order phase transition is ascribed to a strong Pauli paramagnetic suppression in the even-parity pairing. In the normal state above H,2 we found non-Fermi liquid behavior in the temperature dependence of the magnetization down to 150 mK, suggesting the presence of antiferromagnetic fluctuations. (C) 2002 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0022-3697(02)00008-2

    Web of Science

    researchmap

  • Heavy fermions in cerium and uranium compounds studied by the de Haas-van Alphen experiment 査読

    S Araki, R Settai, M Nakashima, H Shishido, S Ikeda, H Nakawaki, Y Haga, N Tateiwa, TC Kobayashi, H Harima, H Yamagami, Y Aoki, T Namiki, H Sato, Y Onuki

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   63 ( 6-8 )   1133 - 1139   2002年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We carried out the de Haas-van Alphen (dHvA) experiment under pressure to clarify the nature of f-electron compounds of CeRh2Si2, UGe2 and CeCoIn5. With increasing pressure, the Neel temperature T-N = 36 K in CeRh2Si2 and the Curie temperature T-C = 52 K in UGe2 decrease, and a quantum critical point corresponding to the extrapolation T-N or T-C --&gt; 0 is reached at the critical pressure p(c) similar or equal to 1.06 and 1.52 GPa, respectively. Experimental results indicate a discontinuous change of the Fermi surface in CeRh2Si2 and UGe2 when the pressure crosses pc. A heavy fermion superconductor CeCoIn5 with a quasi-two dimensional Fermi surface was found to be located in the vicinity of the quantum critical point. (C) 2002 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0022-3697(02)00156-7

    Web of Science

    researchmap

  • Coexistence of antiferromagnetism and superconductivity in heavy-fermion systems 査読

    Y Kitaoka, Y Kawasaki, T Mito, S Kawasaki, GQ Zheng, K Ishida, D Aoki, Y Haga, R Settai, Y Onuki, C Geibel, F Steglich

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   63 ( 6-8 )   1141 - 1146   2002年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We report the novel pressure (P)-temperature (T) phase diagrams of antiferromagnetism (AFM) and superconductivity (SC) in CeRhIn5, CeIn3, and CeCu2Si2 revealed by the nuclear quadrupole resonance measurement. In the itinerant helical magnet CeRhIn5, we found that the Neel temperature T-N is reduced at P greater than or equal to 1.23 GPa with an emergent pseudogap behavior. The coexistence of AFM and SC is found in a narrow P range of 1.63-1.75 GPa, followed by the onset of SC with line-node gap over a wide P window 2.1-5 GPa. In CeIn3, the localized magnetic character is robust against the application of pressure up to P similar to 1.9 GPa, beyond which the system evolves into an itinerant regime in which the resistive superconducting phase emerges. We discuss the relationship between the phase diagram and the magnetic fluctuations. In CeCu2Si2, the SC and AFM coexist on a microscopic level once its lattice parameter is expanded. We remark that the underlying marginal AFM state is due to collective magnetic excitations in the superconducting state in CeCu2Si2. An interplay between AFM and SC is discussed on the SO(5) scenario that unifies AFM and SC. We suggest that the SC and AFM in CeCu2Si2 have a common mechanism. (C) 2002 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0022-3697(02)00133-6

    Web of Science

    researchmap

  • Probing the nodal structure in quasi-2D unconventional superconductors by thermal conductivity 査読

    K Izawa, H Yamaguchi, Y Matsuda, T Sasaki, R Settai, Y Onuki

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   63 ( 6-8 )   1055 - 1059   2002年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The superconducting gap structure is an unresolved issue in most of unconventional superconductors. Here we measured the thermal conductivity of 2D unconventional superconductors, spin-triplet Sr2RuO4, heavy fermion CeCoIn5 and organic kappa-(BEDT-TTF)(2)Cu(NCS)(2), in magnetic field rotating within the 2D planes. On the basis of the angular variation in the thermal conductivity, we demonstrate that the gap function is d(k) = Delta(0)(z) over cap (k(x) + ik(y))(cos ck(z) + alpha) for Sr2RuO4, d(x2-y2) for CeCoIn5, and d(xy). for kappa-(BEDT-TTF)(2)Cu(NCS)(2). (C) 2002 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0022-3697(02)00134-8

    Web of Science

    researchmap

  • Pressure-induced superconductivity in an antiferromagnet CeRh2Si2 査読

    S Araki, M Nakashima, R Settai, TC Kobayashi, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   14 ( 21 )   L377 - L383   2002年6月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We studied the pressure effect by measuring the electrical resistivity for a high-quality single crystal of an antiferromagnet CeRh2Si2 with the tetragonal structure. The Neel temperature becomes zero around I GPa. An onset of superconductivity appears below 0.5 K in a relatively wide pressure region from 0.97 to 1.20 GPa, while the resistivity zero, which appears below 0.4 K, is found to be located in an extremely narrow region from 1.03 to 1.08 GPa. Correspondingly the A value of the Fermi liquid relation in the electrical resistivity (rho = rho(0) + AT(2)) becomes maximum around I GPa. Superconductivity is realized in a heavy fermion state.

    DOI: 10.1088/0953-8984/14/21/102

    Web of Science

    researchmap

  • Unconventional heavy-fermion superconductor CeCoIn5: dc magnetization study at temperatures down to 50 mK 査読

    T Tayama, A Harita, T Sakakibara, Y Haga, H Shishido, R Settai, Y Onuki

    PHYSICAL REVIEW B   65 ( 18 )   2002年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    dc magnetization measurements on CeCoIn5 reveal a first-order phase transition at H-c2 for both Hparallel toa and c axes in the isothermal magnetization M(H) below 0.7 K, indicating a strong Pauli paramagnetic suppression in the even-parity pairing. M(T) in the normal state above H-c2 exhibits non-Fermi-liquid behavior down to 150 mK, implying the existence of antiferromagnetic fluctuations behind the unconventional superconductivity. We observed an unusual peak effect for Hparallel toc in fields 5-30 kOe below 150 mK(=0.06T(c)), whose anomalous temperature dependence cannot be simply explained by ordinary mechanisms.

    DOI: 10.1103/PhysRevB.65.180504

    Web of Science

    researchmap

  • Pressure study of an antiferromagnet, CeMg2Cu9 査読

    H Nakawaki, Y Inada, R Asai, M Yamada, T Okubo, S Ikeda, A Thamizhavel, TC Kobayashi, R Settai, E Yamamoto, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   14 ( 14 )   L305 - L311   2002年4月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We have studied the effect of pressure on the electrical resistivity of the antiferrornagnet CeMg2Cu9 which crystallizes in the hexagonal structure. The structure is built up of alternating MgCu2 Laves-type and CeCu5-type layers along the [0001] direction. The Neel temperature T-N = 2.7 K at ambient pressure decreases with increasing pressure p and disappears at a critical pressure p(e) similar or equal to 2.5 GPa. Correspondingly, the residual resistivity rho(0) and the coefficient A in a Fermi-liquid relation rho = rho(0) + AT(2) are found to have maximum values around p(e).

    DOI: 10.1088/0953-8984/14/14/101

    Web of Science

    researchmap

  • mu SR studies on heavy fermion superconductors CeIrIn5 and CeCoIn5 査読

    W Higemoto, A Koda, R Kadono, Y Kawasaki, Y Haga, D Aoki, R Settai, H Shishido, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   71 ( 4 )   1023 - 1026   2002年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We report that the muon spin relaxation rate under zero-external field in the heavy-fermion compound CeTrIn5 (Tr=Ir. Co) is independent of temperature down to 20 mK, demonstrating the absence of magnetism due to long-range magnetic order and/or to the breakdown of time-reversal symmetry in the superconducting state. The magnetic penetration depth deduced by the muon spin relaxation rate under a transverse field is lambda similar to 6700 Angstrom for CeIrIn5 at 402 G and similar to5500 Angstrom for CeCoIn5 at 3 kG.

    DOI: 10.1143/JPSJ.71.1023

    Web of Science

    researchmap

  • Thermal expansion and magnetostriction studies in a heavy-fermion superconductor, CeCoIn5 査読

    T Takeuchi, H Shishido, S Ikeda, R Settai, Y Haga, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   14 ( 12 )   L261 - L266   2002年4月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We have measured the iso-ficld thermal expansion and magnetostriction in a heavy-fermion superconductor, CeCoIn5, with tetragonal structure. The thermal expansion at zero field shrinks for the [100] direction in the superconducting state, while it expands for [001]. The magnetic field effect on the superconducting transition at the superconducting transition temperature T-c is remarkable for [001]. The longitudinal magnetostriction for H parallel to [001] shows a continuous field dependence with a bend at the upper critical field H-c2 below T-c but this feature changes into a steplike transition below about 0.7 K, indicating that the transition changes from the second to the first order. We have also measured the thermal expansion at high temperatures, which is compared with those in CeIrIn5 and CeRhIn5.

    DOI: 10.1088/0953-8984/14/12/105

    Web of Science

    researchmap

  • Scattering rate of quasiparticles both in the normal and superconducting mixed states in CeCoIn5 studied by the dHvA effect 査読

    R Settai, H Shishido, S Ikeda, M Nakashima, D Aoki, Y Haga, H Harima, Y Onuki

    PHYSICA B-CONDENSED MATTER   312   123 - 125   2002年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We observed the de Haas-van Alphen (dHvA) oscillation both in the normal and superconducting mixed states in a heavy fermion superconductor CeCoIn5. The dHvA oscillation due to a main Fermi surface is observed in the mixed state just below the upper critical field H-c2, indicating a large scattering rate of quasi-particles. We determined the Dingle temperatures both in the normal and the mixed states. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(01)01167-X

    Web of Science

    researchmap

  • Quasi-two-dimensional Fermi surfaces in rare earth and uranium compounds 査読

    Y Onuki, R Settai, D Aoki, H Shishido, Y Haga, Y Tokiwa, H Harima

    PHYSICA B-CONDENSED MATTER   312   13 - 15   2002年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We present the quasi-two-dimensional Fermi surface studies in RTIn5 (R: rare earth, T: Co, Rh and Ir), together with UTGa5. The present quasi-two dimensionality is closely related to the unique crystal structure elongated along the [001] direction, which brings about a flat Brillouin zone and produces cylindrical but highly corrugated Fermi surfaces along [001]. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(01)01155-3

    Web of Science

    researchmap

  • Heat capacity of the pressure-induced superconductivity in itinerant ferromagnet UGe2 査読

    N Tateiwa, TC Kobayashi, K Amaya, Y Haga, R Settai, Y Onuki

    PHYSICA B-CONDENSED MATTER   312   109 - 111   2002年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Recently, co-existence of the ferromagnetism and superconductivity was reported in the high-pressure region (1.0-1.6 GPa) in UGe2. We performed the heat capacity measurement on UGe2 under high pressure. At 1.15 GPa, we found a peak corresponding to the superconducting transition. The superconducting temperature T-sc and DeltaC/(gammaTSC) are 0.6 K and 0.25, respectively. The superconducting transition was also confirmed by the appearance of the Meissner effect in the AC susceptibility. From these results, we confirm a bulk nature of the superconductivity in UGe2. The value of C/T (similar to 95 mJ/molK(2)) just above Tsc at 1.15 GPa is as much as 3 times larger than that at ambient pressure, which indicates a large mass enhancement of quasiparticles under high pressure. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(01)01076-6

    Web of Science

    researchmap

  • Magnetic and Fermi surface properties of UNiGa5 査読

    Y Tokiwa, Y Haga, N Metoki, S Ikeda, R Settai, Y Onuki

    PHYSICA B-CONDENSED MATTER   312   294 - 296   2002年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    In order to investigate the magnetic structure and Fermi surface properties of UNiGa5 we have performed elastic neutron scattering and de Haas-van Alphen(dHvA) experiments. In the neutron scattering experiment using a single crystalline sample, we determined the antiferromagnetic propagation vector Q= (1/2, 1/2,1/2) in UNiGa5. In the dHvA experiment, we observed four branches. Two branches indicate cylindrical Fermi surface and the other two branches correspond to ellipsoidal ones. The cyclotron mass was not large, ranging from 1.3 to 3.1m(0). (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(01)01321-7

    Web of Science

    researchmap

  • de Haas-van Alphen effect in the filled skutterudite CeRu4Sb12 査読

    H Sugawara, K Abe, TD Matsuda, Y Aoki, H Sato, R Settai, Y Onuki

    PHYSICA B-CONDENSED MATTER   312   264 - 266   2002年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have succeeded in observing the de Haas-van Alphen effect in the filled skutterudite CeRu4Sb12. The results predict a large difference in the Fermi surface topology compared to the reference compound LaRu4Sb12. The cyclotron effective mass m(c)* enhanced to 4.6 similar to 5.8m(0) indicates a strong electron correlation in this compound. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(01)01298-4

    Web of Science

    researchmap

  • De Haas-van Alphen effect in UIr 査読

    E Yamamoto, Y Haga, H Shishido, H Nakawaki, Y Inada, R Settai, Y Onuki

    PHYSICA B-CONDENSED MATTER   312   302 - 303   2002年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have succeeded in growing a high-quality single crystal of UIr with the monoclinic structure by the Czochralski pulling method in a tetra-arc furnace. UIr is a ferromagnetic compound. Its Curie temperature T-C is 46 K and the magnetic moment is found to be oriented along the [101] direction by the magnetization measurement. The magnetic moment is 0.5mu(B)/U. We have observed the de Haas-van Alphen oscillation. All the detected branches have heavy cyclotron effective masses ranging from 9.6 to 32m(0). They are consistent with the electronic specific heat coefficient gamma = 48.5 mJ/K-2 mol. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(01)01331-X

    Web of Science

    researchmap

  • De Haas-van Alphen effect in CeRh2Si2 under pressure 査読

    S Araki, M Nakashima, H Nakawaki, R Settai, H Harima, Y Onuki

    PHYSICA B-CONDENSED MATTER   312   435 - 436   2002年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We observed de Haas-van Alphen (dHvA) oscillations in CeRh2Si2 at 1.3 GPa, higher than the quantum critical pressure p(c)similar or equal to1.0 GPa. Three observed dHvA branches correspond to the result of the 4f-itinerant model. Their cyclotron masses are large, being 24m(0), 29m(0) and 31m(0), about 4 times larger than the corresponding band masses. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(01)01359-X

    Web of Science

    researchmap

  • de Haas-van Alphen effect on PrRu4Sb12 査読

    TD Matsuda, K Abe, F Watanuki, H Sugawara, Y Aoki, H Sato, Y Inada, R Settai, Y Onuki

    PHYSICA B-CONDENSED MATTER   312   832 - 833   2002年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The angular dependence of de Haas-van Alphen effect has been measured to reveal the electronic structure of filled skutterudite PrRu4Sb12. The angular dependence of de Haas-van Alphen frequency of PrRu4Sb12 is in good agreement with that of LaRu4Sb12. Compared with PrFe(4)Pi(12), no anomalous enhancement of cyclotron effective mass has been observed in this system. This change of electronic structure is attributed to the difference in the c - f hybridization strength, which is expected from the large difference in the lattice parameters. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(01)01260-1

    Web of Science

    researchmap

  • Angular position of nodes in the superconducting gap of 2D unconventional superconductors 査読

    K Izawa, H Yamaguchi, Y Matsuda, T Sasaki, T Fukase, Y Yoshida, R Settai, Y Onuki

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   367 ( 1-4 )   15 - 19   2002年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The superconducting gap structure, especially the direction of the nodes, is an unresolved issue in most of unconventional superconductors. Here, we have measured the thermal conductivity of 2D unconventional superconductors, spin-triplet Sr2RuO4 and heavy fermion CeCoIn5, in magnetic field rotating within the planes. On the basis of the angular variation of the thermal conductivity, we demonstrate that the gap function of Sr2RuO4 is d(k) = Delta(0)(z) over cap (k(x) + ik(y)) (cos ck(2) + alpha), and the gap function of CeCoIn5 is d(x2-y2). (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4534(01)00979-0

    Web of Science

    researchmap

  • Fermi Surface in CeRh2Si2 under Pressure 査読

    Shingo Araki, Miho Nakashima, Rikio Settai, Hisatomo Harima, Yoshichika Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   71   273 - 275   2002年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We observed the de Haas-van Alphen (dFlvA) oscillations in CeRh2Si2 under pressures up to 1.54 GPa, Three dFIvA branches at higher pressure than the critical pressure p(c) similar or equal to 1.06 GPa, are well explained by the result of the 4f-itinerant model. Their cyclotron masses are large, being 24m(0), 30m(0) and 31m(0), which are about 4 times larger than the corresponding band masses.

    DOI: 10.1143/JPSJS.71S.273

    Web of Science

    researchmap

  • Fermi surface, magnetic and superconducting properties of LaRhIn5 and CeTIn5 (T : Co, Rh and Ir) 査読

    H Shishido, R Settai, D Aoki, S Ikeda, H Nakawaki, N Nakamura, T Iizuka, Y Inada, K Sugiyama, T Takeuchi, K Kindo, TC Kobayashi, Y Haga, H Harima, Y Aoki, T Namiki, H Sato, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   71 ( 1 )   162 - 173   2002年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have studied Fermi surface properties of LaRhIn5 and CeTIa(5) (T: Co, Rh and Ir) via the de Haasvan Alphen (dHvA) experiment. The Fermi surface of a non-4f reference compound LaRhIn5 is quasi-two dimensional, reflecting the unique tetragonal crystal structure, which is consistent with the result of FLAWP energy band calculations. The Fermi surface of an antiferromagnet CeRhIn5 is similar to that of LaRhIn5 although the cyclotron mass in CeRhIn5 is roughly by one order larger than that in LaRhIn5. Both Fermi surfaces are. however, different from those of CeCoIn5 and CcIrIn(5) which are well explained by the 4f-itinerant band model. The 4f electrons in CeRhIn5 thus do not contribute to the volume of ate Fermi surface. We have also studied magnetic and superconducting properties of CeCoIn5 and CeIrIn5.

    DOI: 10.1143/JPSJ.71.162

    Web of Science

    researchmap

  • Pressure-temperature phase diagram of antiferromagnetism and superconductivity in CeRhIn5 and CeIn3: In-115-NQR study under pressure 査読

    S Kawasaki, T Mito, GQ Zheng, C Thessieu, Y Kawasaki, K Ishida, Y Kitaoka, T Muramatsu, TC Kobayashi, D Aoki, S Araki, Y Haga, R Settai, Y Onuki

    PHYSICAL REVIEW B   65 ( 2 )   2002年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report the pressure (P)-temperature (T) phase diagram of antiferromagnetism and superconductivity in CeRhIn5 and CeIn3 revealed by the In-115 nuclear-spin-lattice-relaxation (T-1) measurement. In the itinerant magnet CeRhIn5, we found that the Neel temperature T-N is reduced at P greater than or equal to 1.23 GPa with an emergent pseudogap behavior. In CeIn3, the localized magnetic character is robust against the application of pressure up to Psimilar to1.9 GPa, beyond which the system evolves into an itinerant regime in which the resistive superconducting phase emerges. We discuss the relationship between the phase diagram and the magnetic fluctuations.

    DOI: 10.1103/PhysRevB.65.020504

    Web of Science

    researchmap

  • Exotic heavy-fermion state in the filled skutterudite (formula presented) uncovered by the de Haas-van Alphen effect 査読

    H. Sugawara, T. D. Matsuda, K. Abe, Y. Aoki, H. Sato, S. Nojiri, Y. Inada, R. Settai, Y. Ōnuki

    Physical Review B - Condensed Matter and Materials Physics   66 ( 13 )   1 - 5   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We report the de Haas-van Alphen (dHvA) experiment on the filled skutterudite (formula presented) exhibiting apparent Kondo-like behaviors in the transport and thermal properties. We have found enormously enhanced cyclotron effective mass (formula presented) in the high field phase, which indicates that (formula presented) is the first Pr compound in which really heavy mass has been unambiguously confirmed. Also in the low field nonmagnetic ordered phase (LOP), we observed the dHvA branch with (formula presented) that is quite heavy taking into account its small Fermi surface volume (0.15% of the Brillouin zone size). The insensitivity of mass in LOP against the magnetic field suggests that the quadrupolar interaction plays a main role both in the mass renormalization and the LOP formation. © 2002 The American Physical Society.

    DOI: 10.1103/PhysRevB.66.134411

    Scopus

    researchmap

  • Unconventional heavy-fermion superconductor (formula presented) dc magnetization study at temperatures down to 50 mK 査読

    T. Tayama, A. Harita, T. Sakakibara, Y. Haga, H. Shishido, R. Settai, Y. Onuki

    Physical Review B - Condensed Matter and Materials Physics   65 ( 18 )   1 - 4   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DC magnetization measurements on (formula presented) reveal a first-order phase transition at (formula presented) for both (formula presented) and c axes in the isothermal magnetization (formula presented) below 0.7 K, indicating a strong Pauli paramagnetic suppression in the even-parity pairing. (formula presented) in the normal state above (formula presented) exhibits non-Fermi-liquid behavior down to 150 mK, implying the existence of antiferromagnetic fluctuations behind the unconventional superconductivity. We observed an unusual peak effect for (formula presented) in fields 5-30 kOe below (formula presented) whose anomalous temperature dependence cannot be simply explained by ordinary mechanisms. © 2002 The American Physical Society.

    DOI: 10.1103/PhysRevB.65.180504

    Scopus

    researchmap

  • (formula presented)-NQR evidence for unconventional superconductivity in (formula presented) under pressure 査読

    S. Kawasaki, T. Mito, Y. Kawasaki, G. Zheng, Y. Kitaoka, H. Shishido, S. Araki, R. Settai, Y. Ōnuki

    Physical Review B - Condensed Matter and Materials Physics   66 ( 5 )   1 - 4   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We report evidence for unconventional superconductivity in (formula presented) at a pressure (formula presented) above the critical pressure (formula presented) revealed by measurements of the nuclear-spin-lattice-relaxation time (formula presented) and ac susceptibility (ac- (formula presented) Both measurements of (formula presented) and ac- (formula presented) have pointed to a superconducting transition at (formula presented) which is much lower than the onset temperature (formula presented) at zero resistance. The temperature dependence of (formula presented) shows no coherence peak just below (formula presented) indicative of an unconventional nature for the superconductivity induced in (formula presented). © 2002 The American Physical Society.

    DOI: 10.1103/PhysRevB.66.054521

    Scopus

    researchmap

  • Fermi surface of the heavy-fermion superconductor (formula presented) 査読

    H. Sugawara, S. Osaki, S. R. Saha, Y. Aoki, H. Sato, Y. Inada, H. Shishido, R. Settai, Y. Ōnuki, H. Harima, K. Oikawa

    Physical Review B - Condensed Matter and Materials Physics   66 ( 22 )   1 - 4   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We have investigated the de Haas-van Alphen effect in the Pr-based heavy-fermion superconductor (formula presented) The topology of Fermi surface is close to the reference compound (formula presented) and well explained by the band-structure calculation based on the FLAPW (full potential linearized augmented-plane-wave)-LDA (local-density approximation) (formula presented) method, where the (formula presented) electrons are localized. We have confirmed a highly enhanced cyclotron effective mass (formula presented) which is apparently large compared to the usual Pr-based compounds. © 2002 The American Physical Society.

    DOI: 10.1103/PhysRevB.66.220504

    Scopus

    researchmap

  • Pressure-temperature phase diagram of antiferromagnetism and superconductivity in (formula presented) and (formula presented) (formula presented) study under pressure 査読

    S. Kawasaki, T. Mito, G. Zheng, C. Thessieu, Y. Kawasaki, K. Ishida, Y. Kitaoka, T. Muramatsu, T. C. Kobayashi, D. Aoki, S. Araki, Y. Haga, R. Settai, Y. Onuki

    Physical Review B - Condensed Matter and Materials Physics   65 ( 2 )   1 - 4   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We report the pressure (formula presented)-temperature (formula presented) phase diagram of antiferromagnetism and superconductivity in (formula presented) and (formula presented) revealed by the (formula presented) nuclear-spin-lattice-relaxation (formula presented) measurement. In the itinerant magnet (formula presented) we found that the Néel temperature (formula presented) is reduced at (formula presented) with an emergent pseudogap behavior. In (formula presented) the localized magnetic character is robust against the application of pressure up to (formula presented) beyond which the system evolves into an itinerant regime in which the resistive superconducting phase emerges. We discuss the relationship between the phase diagram and the magnetic fluctuations. © 2001 The American Physical Society.

    DOI: 10.1103/PhysRevB.65.020504

    Scopus

    researchmap

  • Magnetic and electrical properties of UIr

    Etsuji Yamamoto, Yoshinori Haga, Tatsuma D. Matsuda, Akio Nakamura, Rikio Settai, Yoshihiro Inada, Hitoshi Sugawara, Hideyuki Sato, Yoshichika Ōnuki

    Journal of Nuclear Science and Technology   39   187 - 190   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We succeeded in growing a high-quality single crystal of UIr with the monoclinic PbBi-type structure by the Czochralski pulling method in a tetra-arc furnace. The magnetization measurement indicates that UIr is an Ising-like ferromagnet with the Curie temperature TC = 46 K. The magnetic moment is found.to be oriented along the [101] direction in the (010) plane. The saturated moment is 0.5 μB/U. The magnetic property, reflected in the magnetic susceptibility, electrical resistivity, Hall coefficient and thermoelectric power, is highly anisotropic. We also observed the de Haas-van Alphen (dHvA) oscillation. All the detected branches have large cyclotron effective masses ranging from 9.6 to 32 m 0. They are consistent with the electronic specific heat coefficient γ=49 mJ/K2·mol. © 2002 Atomic Energy Society of Japan. All rights reserved.

    DOI: 10.1080/00223131.2002.10875440

    Scopus

    researchmap

  • Evolution of pressure-induced heavy fermion state and superconductivity in (formula presented) A high-pressure Fermi surface study 査読

    H. Shishido, R. Settai, S. Araki, T. Ueda, Y. Inada, T. C. Kobayashi, T. Muramatsu, Y. Haga, Y. Ōnuki

    Physical Review B - Condensed Matter and Materials Physics   66 ( 21 )   1 - 5   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Evolution of the pressure-induced heavy fermion state and superconductivity in (formula presented) have been established by high-pressure Fermi surface studies using dHvA technique. The effective mass of the conduction electrons named branch (formula presented) increases from 5.5 (formula presented) at ambient pressure to 20 (formula presented) at 1.6 GPa where superconductivity sets in. This heavy electron mass continues to increase steeply up to 2.1 GPa, 45 (formula presented) at 2.1 GPa, with a concomitant increase of the superconducting transition temperature. However, the underlying Fermi surface remains approximately same even at 2.1 GPa, strongly suggesting that antiferromagnetic fluctuations of Ce moments do not contribute to the volume of the Fermi surface, but enhance the cyclotron mass of the conduction electrons. © 2002 The American Physical Society.

    DOI: 10.1103/PhysRevB.66.214510

    Scopus

    researchmap

  • Magnetic and fermi surface properties of UCoGa5 and URhGa5 査読

    Shugo Ikeda, Yoshihumi Tokiwa, Tomoyuki Okubo, Yoshinori Haga, Etuji Yamamoto, Yoshihiko Inada, Rikio Settai, Yoshichika Ōnuki

    Journal of Nuclear Science and Technology   39   206 - 209   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We succeeded in growing high-quality single crystals of UCoGa5 and URhGa5 by the self-flux method and measured the electrical resistivity, magnetic susceptibility, and de Hass-van Alphen(dHvA) oscillation. Three kinds of dHvA branches were observed, ranging from 8.6x 105 to 8.1 x 106Oe, which correspond to closed Fermi surfaces. UCoGa5 and URhGas are concluded to be semimetals. The cyclotron mass is small, ranging from 0.6 m 0 to 2.9 m 0. © 2002 Atomic Energy Society of Japan.

    DOI: 10.1080/00223131.2002.10875445

    Scopus

    researchmap

  • De haas-van alphen effect under pressure in UGe2 査読

    Rikio Settai, Yoshinori Haga, Miho Nakashima, Shugo Ikeda, Tomoyuki Okubo, Shingo Araki, Yoshichika Ōnuki

    Journal of Nuclear Science and Technology   39   94 - 97   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The electronic state in UGe2has been studied via the de Haas-van Alphen (dHvA) effect under hydrostatic pressure. The dHvA oscillation has been observed not only in the strongly polarized state (p &lt
    p*c) but also in the weakly polarized (p*c &lt
    p &lt
    pc)and paramagnetic states (p &gt
    pc). The observed Fermi surface, mass enhancement and scattering mechanism are highly different in these states. © 2014 Taylor and Francis Group, LLC.

    DOI: 10.1080/00223131.2002.10875416

    Scopus

    researchmap

  • Fermi surface study on uranium-based intermetallic compounds 査読

    Yoshinori Haga, Etsuji Yamamoto, Yoshihumi Tokiwa, Dai Aoki, Yoshihiko Inada, Rikio Settai, Takahiro Maehira, Hiroshi Yamagami, Hisatomo Harima, Yoshichika Ōnuki

    Journal of Nuclear Science and Technology   39   56 - 62   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Fermi surface properties of various uranium-based intermetallic compounds, including a 5f-localized compound, Pauli paramagnets, heavy fermions, antiferromagnets and ferromagnets, have been investigated by means of the de Haas-van Alphen effect. For this purpose we have grown high-quality single crystals using a purified uranium metal. Both the topology of the Fermi surface and the cyclotron mass in Pauli paramagnets such as USi3 are well explained by the band calculations. Surprisingly, the topology of the Fermi surface in heavy fermions such as UPt3 and UPd2Al3 also agree with the theoretical calculations, except for their unusually large mass enhancement. We have also succeeded in detecting a dHvA oscillation in the superconducting mixed state in the heavy fermion superconductor, UPd2Al3. Spin-polarized band calculatioins are approximately applicable to some magnetically ordered compounds such as UBi2 and UNiGa5. © 2014 Taylor and Francis Group, LLC.

    DOI: 10.1080/00223131.2002.10875408

    Scopus

    researchmap

  • Single Crystal Growth and the High-pressure Effect of an Electronic State in UNiGa5 査読

    Miho Nakashima, Yoshihumi Tokiwa, Hirokazu Nakawaki, Yoshinori Haga, Yoshiya Uwatoko, Rikio Settai, Yoshichika Ōnuki

    Journal of Nuclear Science and Technology   39   214 - 216   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We studied the electronic state of UNiGa5 by measuring the electrical resistivity under pressure. When pressure is applied to UNiGa5, the Néel temperature TN = 86.5 K decreases steeply and becomes zero around 4.5 GPa. Correspondingly, a coeffiecient A in the electrical resistivity of p = p 0 + AT 2, which is a characteristic nature of Fermi liquid, increases steeply with increasing pressure. Around a quantum critical region of about 4.5 GPa, a non-Fermi liquid nature is found, not showing a T 2-dependence of the resistivity. With further increasing pressure above 6 GPa, the Fermi liquid nature recovers completely and the A-value becomes small. © 2002 Atomic Energy Society of Japan.

    DOI: 10.1080/00223131.2002.10875447

    Scopus

    researchmap

  • An unusual hollow cylindrical Fermi surface of a quasi-two-dimensional compound CeAgSb2 査読

    Y. Inada, A. Thamizhavel, H. Yamagami, T. Takeuchi, Y. Sawai, S. Ikeda, H. Shishido, T. Okubo, M. Yamada, K. Sugiyama, N. Nakamura, T. Yamamoto, K. Kindo, T. Ebihara, A. Galatanu, E. Yamamoto, R. Settai, Y. Ōnuki

    Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties   82 ( 18 )   1867 - 1892   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We have carried out the de Haas-van Alphen (dHvA) experiment, together with electrical resistivity, magnetic susceptibility, magnetization and specific heat experiments on a high-quality single-crystal CeAgSb2, which has a small net ferromagnetic moment of 0.4 μB per Ce atom. The bulk magnetic properties are well explained by the crystalline electric field scheme. On the other hand, large dHvA frequencies of 108 Oe, which correspond to cylindrical Fermi surfaces, were detected by the dHvA measurement for the magnetic field along the tetragonal [001] direction, indicating the quasi-two-dimensional electronic structure. The dHvA branches of CeAgSb2 are highly different from those with small dHvA frequencies of 107 Oe for the reference compounds LaAgSb2 and YAgSb2 which exhibit a semimetallic character. The dHvA results have been compared with the results of the energy band calculations. It was concluded that the 4f electron is mainly localized and that the Fermi surface of CeAgSb2 is similar to that of LaAgSb2, but it is slightly enlarged so as to form the large orbits along a hollow cylindrical Fermi surface. © 2002 Taylor and Francis Group, LLC.

    DOI: 10.1080/13642810208222948

    Scopus

    researchmap

  • Evolution of antiferromagntism and superconductivity in CeRhIn5 under pressure.

    S. Kawasaki, T. Mito, G.-q. Zheng, Y. Kawasaki, K. Ishida, Y. Kitaoka, D. Aoki, S. Araki, Y. Haga, R. Settai, Y. Onuki

    J. Phys. Soc. Jpn.   2002年

     詳細を見る

  • Quasi-two dimensional Fermi surfaces in rare earth and uranium compounds: UX2, CeTIn5 and UTGa5 査読

    Y Onuki, D Aoki, P Wisniewski, H Shishido, S Ikeda, Y Inada, R Settai, Y Tokiwa, E Yamamoto, Y Haga, T Maehira, H Harima, M Higuchi, A Hasegawa, H Yamagami

    ACTA PHYSICA POLONICA B   32 ( 10 )   3273 - 3289   2001年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAGIELLONIAN UNIV PRESS  

    We present the quasi-two dimensional Fermi surface studies in rare earth and uranium compounds such as UX2 (X: Bi, Sb, As and P) and RTIn5 (R: rare earth, T: Co, Rh and Ir), together with UTGa5. The present quasi-two dimensionality is closely related to the magnetic unit cell and/or the unique crystal structure elongated along the tetragonal [001] direction, which bring about a flat Brillouin zone and produce cylindrical but highly corrugated Fermi surfaces along [001].

    Web of Science

    researchmap

  • Unconventional superconductivity in CeCoIn5 studied by the specific heat and magnetization measurements (vol 70, pg 2248, 2001) 査読

    S Ikeda, H Shishido, M Nakashima, R Settai, D Aoki, Y Haga, H Harima, Y Aoki, T Namiki, H Sato, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   70 ( 10 )   3187 - 3187   2001年10月

     詳細を見る

    記述言語:英語   出版者・発行元:PHYSICAL SOC JAPAN  

    DOI: 10.1143/JPSJ.70.3187

    Web of Science

    researchmap

  • Unconventional superconductivity in CeCoIn5 studied by the specific heat and magnetization measurements 査読

    S Ikeda, H Shishido, M Nakashima, R Settai, D Aoki, Y Haga, H Harima, Y Aoki, T Namiki, H Sato, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   70 ( 8 )   2248 - 2251   2001年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the low-temperature specific heat in magnetic fields up to 80 kOe. together with the magnetization for the heavy-fermion superconductor CeCoIn5 with the transition temperature T-c = 2.25 K. CeCoIn5, is a strong-coupling superconductor with a large jump in the specific heat, DeltaC/C-n(T-c) = 4.7. The heavy-fermion state is significantly formed below 1 K, reaching at least 1070 mJ/K-2.mol in magnetic fields. This large electronic specific heat coefficient at 0.25 K is. however, reduced with increasing magnetic field, ranging from 1070 mJ/K-2.mol at 50 kOe to 820 mJ/K-2.mol at 80 kOe, The upper critical field H-c2 at 0 K is estimated to be 116 kOe for H // [100] and 49.5 kOe for H // [001]. The present anisotropy of H-c2 is well explained by the anisotropic effective mass. but the magnitude of H-c2 is reduced strongly by the paramagnetic effect for both field directions.

    DOI: 10.1143/JPSJ.70.2248

    Web of Science

    researchmap

  • Observation of large CP violation in the neutral B meson system 査読

    K Abe, K Abe, R Abe, Adachi, I, BS Ahn, H Aihara, M Akatsu, G Alimonti, K Asai, M Asai, Y Asano, T Aso, Aulchenko, V, T Aushev, AM Bakich, E Banas, S Behari, PK Behara, D Beiline, A Bondar, A Bozek, TE Browder, BCK Casey, P Chang, Y Chao, KF Chen, BG Cheon, R Chistov, SK Choi, Y Choi, LY Dong, J Dragic, A Drutskoy, S Eidelman, Eiges, V, Y Enari, R Enomoto, CW Everton, F Fang, H Fujii, C Fukunaga, M Fukushima, N Gabyshev, A Garmash, TJ Gershon, A Gordon, K Gotow, H Guler, R Guo, J Haba, H Hamasaki, K Hanagaki, F Handa, K Hara, T Hara, NC Hastings, H Hayashii, M Hazumi, EM Heenan, Y Higasino, Higuchi, I, T Higuchi, T Hirai, H Hirano, T Hojo, T Hokuue, Y Hoshi, K Hoshina, Hou, SR, WS Hou, SC Hsu, HC Huang, Y Igarashi, T Iijima, H Ikeda, K Ikeda, K Inami, A Ishikawa, H Ishino, R Itoh, G Iwai, H Iwasaki, Y Iwasaki, DJ Jackson, P Jalocha, HK Jang, M Jones, R Kagan, H Kakuno, J Kaneko, JH Kang, JS Kang, P Kapusta, N Katayama, H Kawai, H Kawai, Y Kawakami, N Kawamura, T Kawasaki, H Kichimi, DW Kim, H Kim, HJ Kim, H Kim, SK Kim, TH Kim, K Kinoshita, S Kobayashi, S Koishi, H Konishi, K Korotushenko, P Krokovny, R Kulasiri, S Kumar, T Kuniya, E Kurihara, A Kuzmin, YJ Kwon, JS Lange, G Leder, MH Lee, SH Lee, C Leonidopoulos, YS Lin, D Liventsev, RS Lu, J MacNaughton, D Marlow, T Matsubara, S Matsui, S Matsumoto, T Matsumoto, Y Mikami, K Misono, K Miyabayashi, H Miyake, H Miyata, LC Moffitt, GR Moloney, GF Moorhead, S Mori, T Mori, A Murakami, T Nagamine, Y Nagasaka, Y Nagashima, T Nakadaira, T Nakamura, E Nakano, M Nakao, H Nakazawa, JW Nam, Z Natkaniec, K Neichi, S Nishida, O Nitoh, S Noguchi, T Nozaki, S Ogawa, T Ohshima, Y Ohshima, T Okagbe, T Okazaki, S Okuno, SL Olsen, H Ozaki, P Pakhlov, H Palka, CS Park, CW Park, H Park, LS Peak, M Peters, LE Piilonen, E Prebys, JL Rodriguez, N Root, M Rozanska, K Rybicki, J Ryuko, H Sagawa, Y Sakai, H Sakamoto, M Satapathy, A Satpathy, S Schrenk, S Semenov, K Senyo, Y Settai, ME Sevior, H Shibuya, B Shwartz, A Sidorov, S Stanic, A Sugi, A Sugiyama, K Sumisawa, T Sumiyoshi, JI Suzuki, K Suzuki, S Suzuki, SY Suzuki, SK Swain, H Tajima, T Takahashi, F Takasaki, M Takita, K Tamai, N Tamura, J Tanaka, M Tanaka, GN Taylor, Y Teramoto, M Tomoto, T Tomura, SN Tovey, K Trabelsi, T Tsuboyama, T Tsukamoto, S Uehara, K Ueno, M Unno, S Uno, Y Ushiroda, SE Vahsen, KE Varvell, CC Wang, CH Wang, JG Wang, MZ Wang, Y Watanabe, E Won, BD Yabsley, Y Yamada, M Yamaga, A Yamaguchi, H Yamamoto, T Yamanaka, Y Yamashita, M Yamauchi, S Yanaka, J Yashima, M Yokoyama, K Yoshida, Y Yusa, H Yuta, CC Zhang, J Zhang, HW Zhao, Y Zheng, Zhilich, V, D Zontar

    PHYSICAL REVIEW LETTERS   87 ( 9 )   2001年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We present a measurement of the standard model CP violation parameter sin2 phi (1) based on a 29.1 fb(-1) data sample collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson is fully reconstructed as a J/psiK(S), psi (2S)K(S), X(c1)K(S), eta (c)K(S), J/psiK(L), or J/psiK*(0) decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin2 phi (1) = 0.99 +/-0.14(stat) +/-0.06(syst). We conclude that we have observed CP violation in the neutral B meson system.

    DOI: 10.1103/PhysRevLett.87.091802

    Web of Science

    researchmap

  • Pressure-induced superconductivity in a ferromagnet UGe2 (vol 13, pg L17, 2001) 査読

    N Tateiwa, TC Kobayashi, K Hanazono, K Amaya, Y Haga, R Settai, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   13 ( 29 )   6443 - 6443   2001年7月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    DOI: 10.1088/0953-8984/13/29/501

    Web of Science

    researchmap

  • Angular position of nodes in the superconducting gap of quasi-2D heavy-fermion superconductor CeCoIn5 査読

    K Izawa, H Yamaguchi, Y Matsuda, H Shishido, R Settai, Y Onuki

    PHYSICAL REVIEW LETTERS   87 ( 5 )   2001年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    The thermal conductivity of the heavy-fermion superconductor CeCoIn5 has been studied in a magnetic field rotating within the 2D planes. A clear fourfold symmetry of the thermal conductivity which is characteristic of a superconducting gap with nodes along the (+/- pi, +/- pi) directions is resolved. The thermal conductivity measurement also reveals a first-order transition at H-c2, indicating a Pauli limited superconducting state. These results indicate that the symmetry most likely belongs to d(x2-y2), implying that the anisotropic antiferromagnetic fluctuation is relevant to the superconductivity.

    DOI: 10.1103/PhysRevLett.87.057002

    Web of Science

    researchmap

  • Quadrupolar phase diagram and Fermi surface properties in the localized 5f(2)-electron system UPd3 査読

    Y Tokiwa, K Sugiyama, T Takeuchi, M Nakashima, R Settai, Y Inada, Y Haga, E Yamamoto, K Kindo, H Harima, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   70 ( 6 )   1731 - 1743   2001年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the electrical resistivity, specific heat, magnetostriction, magnetization and de Haas-van Alphen (dHvA) oscillation in UPd3 with the hexagonal structure in order to clarify the quadrupolar and magnetic properties as well as the nature of conduction electrons. The high-field magnetization measurement at 4.2 K in magnetic fields up to about 50 T reveals two-successive metamagnetic transitions at 10.2 and 17.9T for the field along the [0001] direction, and one transition at 27.6T along [1120]. From the results of magnetization as well as the magnetostriction measurements at various temperatures, we determined the magnetic phase diagram. Phase boundaries are discussed on the basis of the crystalline electric field scheme of the 5f(2) configuration and the quadrupolar interaction of O-ZX. Reflecting title localized 5f-electrons, the conduction electrons have small cyclotron effective masses ranging from 0.24 to 3.62m(0), which were determined by the dHvA experiment. The dHvA data are compared to the result of band calculations based on the 5f(2)-localized band model.

    DOI: 10.1143/JPSJ.70.1731

    Web of Science

    researchmap

  • Single crystal growth and de Haas-van Alphen effect of TmAl3 査読

    T Ebihara, D Aoki, Y Inada, R Settai, K Sugiyama, Y Haga, Y Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   226   101 - 102   2001年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We succeeded in growing single crystals of TmAl3 with the AuCu3-type cubic structure, This compound is a reference for a heavy-fermion compound YbAl3. The single crystals were grown by the self-flux method. We observed de Haas-van Alphen oscillation. (C) 2001 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0304-8853(00)01133-1

    Web of Science

    researchmap

  • Observation of heavy electrons in the filled skutterudite PrFe4P12 via the de Haas-van Alphen effect 査読

    H Sugawara, TD Matsuda, K Abe, Y Aoki, S Nojiri, Y Inada, R Settai, Y Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   226   48 - 50   2001年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have succeeded in observing the de Haas-van Alphen (dHvA) oscillations in the filled skutterudite PrFe4P12. The results predict a large difference in topology of the Fermi surface compared to the reference compound LaFe4P12. The cyclotron effective mass is found to be extraordinarily enhanced with the maximum value of 67m(0). (C) 2001 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0304-8853(00)00764-2

    Web of Science

    researchmap

  • High-quality single-crystal growth and a change of the electronic states under pressure in CeRh2Si2 査読

    S Araki, R Settai, TC Kobayashi, Y Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   226   80 - 82   2001年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We succeeded in growing a high-quality single crystal of CeRh2Si2 with a residual resistivity ratio of 110. Under a pressure of 1.1 GPa, superconductivity is found below T-c = 0.38 K. where a Neel temperature of T-N = 36 K is suppressed down to almost zero. (C) 2001 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0304-8853(00)00785-X

    Web of Science

    researchmap

  • Pressure effects of susceptibility and specific heat in PrCu2 査読

    T Naka, J Tang, P Ahmet, R Settai, Y Onuki

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   226   1008 - 1010   2001年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The pressure effects on magnetic susceptibility, specific heat and the co-operative Jahn-Teller transition temperature, T-JT, in the single crystalline sample are presented. At P = 1.2 GPa susceptibility shows remarkable maximum at T = T-max while specific heat shows no anomalous change around T-max. However, at T much less than T-JT the upturn of nuclear specific heat is developed with pressure. Our findings imply that a magnetic ordering is induced by pressure. (C) 2001 Published by Elsevier Science B.V.

    DOI: 10.1016/S0304-8853(01)00111-1

    Web of Science

    researchmap

  • Superconducting gap structure of spin-triplet superconductor Sr2RuO4 studied by thermal conductivity 査読

    K Izawa, H Takahashi, H Yamaguchi, Y Matsuda, M Suzuki, T Sasaki, T Fukase, Y Yoshida, R Settai, Y Onuki

    PHYSICAL REVIEW LETTERS   86 ( 12 )   2653 - 2656   2001年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    To clarify the superconducting gap structure of the spin-triplet superconductor Sr2RuO4, the in-plane thermal conductivity has been measured as a function of relative orientations of the thermal flow, the crystal axes, and a magnetic field rotating within the 2D RUO2 planes. The in-plane variation of the thermal conductivity is incompatible with any model with line nodes vertical to the 2D planes and indicates the existence of horizontal nodes. These results place strong constraints on models that attempt to explain the mechanism of the triplet superconductivity.

    DOI: 10.1103/PhysRevLett.86.2653

    Web of Science

    researchmap

  • Ultrasonic studies of the spin-triplet order parameter and the collective mode in Sr2RuO4 査読

    H Matsui, Y Yoshida, A Mukai, R Settai, Y Onuki, H Takei, N Kimura, H Aoki, N Toyota

    PHYSICAL REVIEW B   63 ( 6 )   2001年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The elastic constant C-T and ultrasonic attenuation alpha (s) for (C-11-C-12)/2 have been measured on Sr2RuO4 with T-c*= 1.42 K. In contrast to the A(1g) and E-g strains, the B-1g strain (epsilon (xx)-epsilon (yy)) strongly couples to the superconducting state, which dominantly originate from hybridized Ru-4d(xy) electrons on the gamma Fermi surface. Taken into account impurity induced in-gap states, the T-3 dependence of alpha (s) is found to be consistent with an existence of line nodes. The large reduction in CT below T-c* evidences the two-component order parameter and chiral p-wave state. Anomalous C-T and alpha (s) around T-a = 1.34 K suggest a collective mode.

    DOI: 10.1103/PhysRevB.63.060505

    Web of Science

    researchmap

  • Shubnikov-de Haas effect study of cylindrical Fermi surfaces in UP2 査読

    P Wisniewski, D Aoki, N Watanabe, R Settai, Y Haga, E Yamamoto, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   70 ( 1 )   278 - 283   2001年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Shubnikov-de Haas effect (SdH) measurements and complementary electrical resistivity and specific heat measurements were performed on a high-quality whisker single crystal of UP2. All except one of detected branches exhibit angular dependences clearly indicating the Fermi surfaces (FS) of cylindrical form. The effective cyclotron masses were determined to range from 1.9 to 9.3 mo, which yields an electronic specific heat coefficient of 25 mJ/K-2.mol. This is in good agreement with 27 mJ/K-2.mol determined directly by the low-temperature specific-heat measurement. As in sister compounds UAs2, USb2 and UBi2, the two-dimensional Fermi surfaces are formed in the flattened magnetic Brillouin zone and the conduction electrons are confined mainly in the U planes. Significant contribution of itinerant 5 integral electrons to the conduction band is concluded from rather big effective cyclotron masses.

    DOI: 10.1143/JPSJ.70.278

    Web of Science

    researchmap

  • Pressure-induced superconductivity in a ferromagnet UGe2 査読

    N Tateiwa, TC Kobayashi, K Hanazono, K Amaya, Y Haga, R Settai, Y Onuki

    JOURNAL OF PHYSICS-CONDENSED MATTER   13 ( 1 )   L17 - L23   2001年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We confirmed bulk-superconductivity of a ferromagnet UGe2 by the specific heat measurement, together with the measurements of the electrical resistivity and ac susceptibility, in a pressure range from p = 1.0 to 1.5 GPa, where the Curie temperature T-C(= 22-36 K) is still high, but another characteristic temperature T* is close to zero. In this pressure range, the heavy fermion state is found to be formed at low temperatures.

    DOI: 10.1088/0953-8984/13/1/103

    Web of Science

    researchmap

  • Ultrasonic studies of the spin-triplet order parameter and the collective mode in Sr2RuO4 査読

    H. Matsui, Y. Yoshida, A. Mukai, R. Settai, Y. Ōnuki, H. Takei, N. Kimura, H. Aoki, N. Toyota

    Physical Review B - Condensed Matter and Materials Physics   63 ( 6 )   605051 - 605054   2001年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The elastic constant CT and ultrasonic attenuation αs for (C11-C12)/2 have been measured on Sr2RuO4 with Tc * = 1.42 K. In contrast to the A1g and Eg strains, the B1g strain (εxx - εyy) strongly couples to the superconducting state, which dominantly originate from hybridized Ru-4dxy electrons on the γ Fermi surface. Taken into account impurity induced in-gap states, the T3 dependence of αs is found to be consistent with an existence of line nodes. The large reduction in CT below Tc * evidences the two-component order parameter and chiral p-wave state. Anomalous CT and αs around Ta= 1.34 K suggest a collective mode.

    DOI: 10.1103/PhysRevB.63.060505

    Scopus

    researchmap

  • Acoustic de Haas-van Alphen effect and elastic anomaly of transverse mode (C-11- C-12)/2 in Sr2RuO4 査読

    H Matsui, Y Yoshida, A Mukai, R Settai, Y Onuki, H Takei, N Kimura, H Aoki, N Toyota

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   69 ( 12 )   3769 - 3772   2000年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The acoustic de Haas-van Alphen (dHvA) effect and temperature dependence of the transverse mode (C-11 - C-12)/2 have been measured in a layered Perovskite superconductor Sr2RUO4 With T-c* = 1.42 K. From the acoustic dHvA oscillations for alpha and beta orbits along [001], the area coefficients are estimated to be \Lambda (alpha)(B1g)\ = 0.8 and \Lambda (beta)(B1g)\ = 0.2 similar to 0.3. Both Fermi surfaces consisting of hybridized Ru-4d(xx(yz)) orbitals couple weakly to epsilon (xx) - epsilon (yy), because the in-plane shear strain hardly varies the spacing between the alternating RuO2 layers. Large softening occurs below 220 K, which corresponds to the rotational instability. The rotational deformation of the RuO6 octahedron is induced perturbingly by epsilon (xx) - epsilon (yy) which reduces the lattice matching.

    DOI: 10.1143/JPSJ.69.3769

    Web of Science

    researchmap

  • The Fermi surface in filled skutterudite RFe4P12 (R=La and Nd) 査読

    H Sugawara, Y Abe, Y Aoki, H Sato, M Hedo, R Settai, Y Onuki, H Harima

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   69 ( 9 )   2938 - 2946   2000年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have investigated the de Haas-van Alphen (dHvA) effect and the transverse magnetoresistance in filled skutterudite LaFe4P12 and NdFe4P12. The Fermi surface of LaFe4P12 consists of a nearly spherical hole sheet and a multiply connected one. These features are explained reasonably well by a full potential linearized augmented-plane-wave (FLAPW) band structure calculation, The Fermi surface of NdFe4P12 is similar to those in LaFe4P12 except the exchange splitting in the dHvA frequencies. The cyclotron effective masses are enhanced roughly twice compared to those of LaFe4P12 due to the electron-magnon interaction.

    DOI: 10.1143/JPSJ.69.2938

    Web of Science

    researchmap

  • Bulk 4f electronic states of Ce-based heavy fermion system probed by high-resolution resonance photoemission 査読

    A Sekiyama, K Kadono, K Matsuda, T Iwasaki, S Ueda, S Imada, S Suga, R Settai, H Azuma, Y Onuki, Y Saitoh

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   69 ( 9 )   2771 - 2774   2000年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    "Bulk-sensitive" Ce 3d - 4f resonance photoemission (RPES) with an unprecedentedly high resolution has revealed a clear difference of bulk Ce 4f spectral weights of heavy fermion system CeRu2Si2 and CeRu2Ge2 in the region of the tail of the Kondo peak and its spin-orbit partner. The significant spectral difference in both materials is in strong contrast to the mutually similar "surface-sensitive" 4d - 4f RPES. The obtained bulk-sensitive spectra are well reproduced by a single impurity model. Consideration of the crystalline electric field splitting is important for estimating a realistic Kondo temperature from the bulk 4f spectra.

    DOI: 10.1143/JPSJ.69.2771

    Web of Science

    researchmap

  • Fermi surface properties of the enhanced Pauli paramagnet UAl3 査読

    D Aoki, N Watanabe, Y Inada, R Settai, K Sugiyama, H Harima, T Inoue, K Kindo, E Yamamoto, Y Haga, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   69 ( 8 )   2609 - 2614   2000年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing a high-quality single crystal of UAl3 with the cubic AuCu3-type structure and studied the :Fermi surface properties by measuring the de Haas-van Alphen (dHvA) effect and the magnetoresistance, together with the electrical resistivity, magnetic susceptibility and specific heat. Seven dHvA branches were observed, ranging from 1.1 x 10(6) to 1.5 x 10(8) Oe. These branches are partially explained by the result of band calculations based on the 5f-itinerant band model. The detected cyclotron mass is in the range from 3 to 17 m(0), suggesting the strong 5f hybridization with the conduction electrons, which is twice to three times larger than the corresponding band mass.

    DOI: 10.1143/JPSJ.69.2609

    Web of Science

    researchmap

  • Magnetic domain structure in a hyperfine-enhanced nuclear magnet PrCu6 査読

    H Inaba, K Kawasaki, A Matsubara, O Ishikawa, T Hata, T Kodama, A Koyanagi, R Settai, Y Onuki

    PHYSICA B   284   1692 - 1693   2000年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Magnetization curve measurement in the spin-ordered state of an enhanced nuclear magnet PrCu6 has been carried out. Hysteresis due to a ferromagnetic domain structure is observed. The hysteresis appears when the magnetic field is applied along the c-axis, but not along the b-axis. This strongly anisotropic behavior suggests that a possible spin structure in the ordered state is a canted ferromagnet: ferromagnetically aligned along the c-axis with magnetic domains but antiferromagnetically along b-axis. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)02926-9

    Web of Science

    researchmap

  • DHvA oscillation in the anisotropic superconductors of UPd2Al3 and URu2Si2 査読

    Y Inada, Y Haga, H Ohkuni, Y Tokiwa, R Settai, T Honma, E Yamamoto, Y Onuki

    PHYSICA B   284   523 - 524   2000年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    UPd2Al3 and URu2Si2 are considered to be non-s-wave superconductors with an anisotropic energy gap from the NMR and specific heat measurements. We have succeeded in observing clearly the dHvA oscillation in both the normal and superconducting mixed states. The cyclotron mass is found to be reduced and the Dingle temperature increases in the mixed state. An anisotropic energy gap with a line node for UPd2Al3 and URu2Si2 was discussed from the angular dependence of the dHvA amplitude in the mixed state. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)02122-5

    Web of Science

    researchmap

  • High-field magnetization and thermal expansion of UPd3 査読

    T Takeuchi, Y Tokiwa, K Sugiyama, R Settai, Y Haga, E Yamamoto, T Honma, K Kindo, Y Onuki

    PHYSICA B   284   1285 - 1286   2000年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Iso-field thermal expansion and high-field magnetization measurements have been performed on a single-crystalline UPd3 to study the antiferromagnetic ordering as well as the quadrupolar one. The magnetic phase diagram was obtained. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)02559-4

    Web of Science

    researchmap

  • Fermi surface and superconducting properties in Sr<inf>2</inf> RuO<inf>4</inf>

    Y. Yoshida, Y. Yoshida, Y. Yoshida, A. Mukai, K. Miyake, N. Watanabe, R. Settai, Y. Onuki, T. D. Matsuda, Y. Aoki, H. Sato, Y. Miyamoto, N. Wada

    Physica B: Condensed Matter   281-282   959 - 960   2000年6月

     詳細を見る

    We measured the low-temperature specific heat and de Haas-van Alphen oscillation in Sr2RuO4. The electronic specific heat Ce follows a T2-dependence below 0.7 K for the sample with a superconducting critical temperature Tc = 1.52 K, suggesting line nodes in the superconducting gap. Three kinds of cylindrical Fermi surfaces were discussed from a view point of their cyclotron effective masses. © 2000 Elsevier Science B.V. All rights reserved.

    Scopus

    researchmap

  • Pressure effect on the cooperative Jahn-Teller transition in PrCu2 査読

    S Takayanagi, H Tatta, A Miyashita, R Settai, Y Onuki, N Mori

    PHYSICA B   281   583 - 585   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have studied pressure dependence on the cooperative Jahn-Teller specific heat in the orthorhombic PrCu2 using a clamp-type pressure-cell. The pressure in the clamp-type pressure-cell is determined from the superconducting transition temperatures of Sn (999.99%) at liquid-helium temperatures. The pressure is ineffective on the specific heat for PrCu2 up to 0.8 GPa below 5 K. Above 5 K, obvious depression in the specific heat peak is observed as pressure increases. The Jahn-Teller transition temperature T-C increases with increasing pressure. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)01069-8

    Web of Science

    researchmap

  • Metamagnetism of uranium heavy-fermion compounds UPd2Al3, URu2Si2 and UPt3 査読

    K Sugiyama, M Nakashima, M Futoh, H Ohkuni, T Inoue, K Kindo, N Kimura, E Yamamoto, Y Haga, T Honma, R Settai, Y Onuki

    PHYSICA B   281   244 - 246   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The high-field magnetization masurements in UPd2Al3, URu2Si2 and UPt3 were carried out up to 55 T at various temperatures. We determined their phase diagrams. The metamagnetic transitions for these compounds were observed up to the characteristic temperatures showing the maxima of the magnetic susceptibilities. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)00926-6

    Web of Science

    researchmap

  • Thermal expansion and magnetostriction of UPd3 査読

    T Takeuchi, Y Tokiwa, R Settai, Y Haga, E Yamamoto, T Honma, Y Onuki

    PHYSICA B   281   602 - 603   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We measured the thermal expansion coefficient and magnetostriction for UPd3 with the hexagonal structure. The temperature dependence of the thermal expansion coefficient was well explained by the crystalline electric field model with the quadrupolar interaction. Three phase transitions at 4.6. 6.8 and 7.8 K were studied precisely by the magnetostriction measurements. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)00927-8

    Web of Science

    researchmap

  • Quadrupolar ordering and de Haas-van Alphen effect in UPd3 査読

    Y Tokiwa, K Sugiyama, T Takeuchi, R Settai, Y Inada, Y Haga, E Yamamoto, T Honma, K Sakurai, M Nakashima, K Miyake, K Kindo, Y Onuki

    PHYSICA B   281   604 - 605   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We determined the magnetic phase diagram of UPd3 with the hexagonal structure. There are three successive phase transitions at 7.5, 6.8 and 4.5 K. This first transition is due to the quadrupolar ordering, which was qualitatively discussed on the basis of the quadrupolar interaction with the order parameter O-zx. The de Haas-van Alphen experiments were also done to clarify the Fermi surface property. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)00899-6

    Web of Science

    researchmap

  • Fermi surfaces of RIn3 (R = Tb, Dy, Ho, Er, Tm, Yb and Lu) 査読

    S Nojiri, Y Katayama, D Aoki, N Suzuki, K Sugiyama, R Settai, Y Inada, Y Onuki, H Harima

    PHYSICA B   281   747 - 749   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We observed the de Haas-van Alphen (dHvA) oscillations in RIn3 (R = Tb, Dy, Ho, Er, Tm Yb and Lu). The Fermi surfaces in each RIn3 are compared to the results of FLAPW band calculations. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)00902-3

    Web of Science

    researchmap

  • Single-crystal growth by flux method and Fermi surface of uranium compounds 査読

    D Aoki, P Wisniewski, K Miyake, R Settai, Y Inada, K Sugiyama, E Yamamoto, Y Haga, Y Onuki

    PHYSICA B   281   761 - 763   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have grown single crystals of UGa3, USb2 and UBi2 by the self-flux method and measured the de Haas-van Alphen (dHvA) oscillations. The detected Fermi surfaces were five closed ones in an antiferromagnetic compound UGa3. The cylindrical Fermi surfaces were observed for USb2 and UBI2, which manifests the two-dimensional character on the conduction electrons. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)00843-1

    Web of Science

    researchmap

  • Hall effect and thermoelectric power in CeCu5.9Au0.1 and CeCu6 査読

    T Namiki, H Sato, J Urakawa, H Sugawara, Y Aoki, R Settai, Y Onuki

    PHYSICA B   281   359 - 360   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have investigated the Hall coefficient (R-H) and thermoelectric power (TEP)bn single crystals of CeCu5.9Au0.1, which shows non-Fermi liquid anomaly, and on CeCu6 as a reference. TEP exhibits a large positive peak at similar to 40 K, below which it becomes highly anisotropic. Au substitution causes no drastic change in TEP. The anisotropy in R-H(T) is small above 10 K, and it showed a large dependence on the held direction in both compounds below 10 K. Most interesting aspect of the present results is the large anisotropy in the Au substitution effect on RH(T), which might correlate with the anisotropy in the spin fluctuation. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)01053-4

    Web of Science

    researchmap

  • Metamagnetic transition of CeRh2Si2 under high fields and high pressures at various temperatures 査読

    T Hamamoto, K Kindo, TC Kobayashi, Y Uwatoko, S Araki, R Settai, Y Onuki

    PHYSICA B   281   64 - 65   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    High-field magnetization measurements in a heavy fermion antiferromagnet CeRh2Si2 were performed under high pressures at various temperatures to study the nature of the metamagnetism. Metamagnetic transitions were observed not only in the antiferromagnetic state but also in the paramagnetic stale at various pressures, The metamagnetism in CeRh2Si2 does not originate from the rearrangement of antiferromagnetic moments but from the recovery of the local moment from the Kondo singlet state by applying high magnetic fields. (C) 2000 Published by Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)00973-4

    Web of Science

    researchmap

  • Electrodynamic response at metamagnetic anomaly in CeRu2Si2 査読

    H Matsui, T Yasuda, A Misawa, R Settai, E Yamamoto, Y Haga, Y Onuki, N Toyota

    PHYSICA B-CONDENSED MATTER   281   56 - 58   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Microwave cavity transmission experiments have been carried out to clarify the dynamic response due to the dielectric function epsilon(omega) and the magnetic permeability mu(omega) in CeRu2Si2. The anomaly for both epsilon(omega) and mu(omega) emerges at the metamagnetic field H-M = 7.7 T below 1 K, whereas the B-T phase diagram provided by the dynamic response is different from that for the static one. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)01058-3

    Web of Science

    researchmap

  • Itinerant f-electron systems of cerium and uranium compounds 査読

    Y Onuki, Y Inada, H Ohkuni, R Settai, N Kimura, H Aoki, Y Haga, E Yamamoto

    PHYSICA B   280 ( 1-4 )   276 - 280   2000年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The f-electron systems of the cerium and uranium compounds have attracted attention in the context of heavy fermion and anisotropic superconductivity. We clarified an itinerant f-electron nature for UPt3 by the de Haas-van Alphen experiments, detecting heavy conduction electrons with 100m(0). The dHvA oscillation was also observed clearly in both the normal and superconducting mixed states in CeRu2,URu2Si2 and UPd2Al3. An anisotropic energy gap with a line node for URu2Si2 was discussed from the angular dependence of the dHvA amplitude in the mixed state. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(99)01684-1

    Web of Science

    researchmap

  • Fermi surface properties of USi3 査読

    Y Tokiwa, H Harima, D Aoki, S Nojiri, M Murakawa, K Miyake, N Watanabe, R Settai, Y Inada, H Sugawara, H Sato, Y Haga, E Yamamoto, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   69 ( 4 )   1105 - 1112   2000年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We succeeded in growing a single crystal of USi3 with the cubic crystal structure and measured the transverse magnetoresistance and de Haas-van Alphen(dHvA) oscillation. Fifteen dHvA branches were observed, ranging from 7.37x10(6) to 2.33x10(8) Oe. These branches are in good agreement with theoretical ones based on 5f-itinerant FLAPW band calculations. Cyclotron masses, which are in the range from 0.39 to 4.17 m(0), are approximately the same as the corresponding band masses. These results indicate that the itinerant 5f-electrons form wide bands. The magnetoresistance results confirmed the existence of open orbits, which can he well explained by the band 10-electron Fermi surface.

    DOI: 10.1143/JPSJ.69.1105

    Web of Science

    researchmap

  • Cylindrical Fermi surfaces formed by a flat magnetic Brillouin zone in uranium dipnictides 査読

    D. Aoki, P. Wiśniewski, K. Miyake, N. Watanabe, Y. Inada, R. Settai, E. Yamamoto, Y. Haga, Y. Onuki

    Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties   80 ( 8 )   1517 - 1544   2000年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Taylor and Francis Inc.  

    We succeeded in growing high-quality single crystals of UX2 (X = Bi, Sb, As or P) by the self-flux and chemical transport methods and carried out de Haas-van Alphen and Shubnikov-de Haas experiments. We found quasi-two-dimensional Fermi surfaces in these U compounds. Fermi surfaces of UBi2 are found to consist of one spherical Fermi surface and two cylindrical Fermi surfaces. Each Fermi surface in UBi2 changes into two cylindrical surfaces in USb2 and UAs2. This change in the Fermi surfaces is well explained on the basis of a flat magnetic Brillouin zone. The quasi-two-dimensional character of the Fermi surfaces is mainly due to the conduction electrons in the U plane, including the 5f electrons. The itinerant nature of 5f electrons is reflected in the large cyclotron masses. The magnetic breakthrough (breakdown) phenomenon is also discussed for USb2.

    DOI: 10.1080/13642810008208582

    Scopus

    researchmap

  • Magnetic phase diagram in UCd11 査読

    D Aoki, T Inoue, K Kindo, N Suzuki, K Miyake, Y Inada, R Settai, K Sugiyama, E Yamamoto, Y Haga, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   68 ( 9 )   3117 - 3118   1999年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOCIETY JAPAN  

    DOI: 10.1143/JPSJ.68.3117

    Web of Science

    researchmap

  • Fermi surface properties and de Haas-van Alphen oscillation in both the normal and superconducting mixed states of URu2Si2 査読

    H Ohkuni, Y Inada, Y Tokiwa, K Sakurai, R Settai, T Honma, Y Haga, E Yamamoto, Y Onuki, H Yamagami, S Takahashi, T Yanagisawa

    PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES   79 ( 7 )   1045 - 1077   1999年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TAYLOR & FRANCIS LTD  

    We have succeeded in growing a high-quality single crystal of URu2Si2 with a residual resistivity ratio of 255 and performed magnetoresistance and de Haas-van Alphen (dHvA) experiments. The dHvA oscillations were observed clearly in both the normal and superconducting mixed states. From the magnetoresistance experiments, it is concluded that URu2Si2 is a compensated metal with equal carrier numbers of electrons and holes. In the dHvA experiments we observed three kinds of Fermi surfaces. We studied precisely the Fermi surface properties in both the normal and mixed states. The dHvA frequency does not change in magnitude between the normal and mixed states, while the cyclotron effective mass is reduced, and the corresponding Dingle temperature or scattering rate of the conduction electron increases in the mixed state.

    DOI: 10.1080/014186399256916

    Web of Science

    researchmap

  • Crystal growth and cylindrical Fermi surfaces of USb2 査読

    D Aoki, P Wisniewski, K Miyake, N Watanabe, Y Inada, R Settai, E Yamamoto, Y Haga, Y Ouki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   68 ( 7 )   2182 - 2185   1999年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have gown high-quality single crystals of tetragonal USb2 using a flux method. We have detected five branches in de Haas-van Alphen (dHvA) experiments. Frequencies of all dHvA branches follow the 1/cos theta-dependence, revealing the presence of cylindrical Fermi surfaces, where theta is a tilt angle from [001] to [100]. The cyclotron masses are in the range from 1.84 to 8.33 m(0). The two-dimensional Fermi surfaces are due to the conduction electrons in the U-plane, including the itinerant 5f-electrons.

    DOI: 10.1143/JPSJ.68.2182

    Web of Science

    researchmap

  • Electrical and thermal properties of UB2 査読

    E Yamamoto, T Honma, Y Haga, Y Inada, D Aoki, N Suzuki, R Settai, H Sugawara, H Sato, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   68 ( 3 )   972 - 975   1999年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have measured the electrical resistivity, thermoelectric power, magnetic susceptibility, magnetoresistance and specific heat of a Pauli paramagnetic compound UB2. The magnetoresistance shows an extremely large H-2-dependence for any field directions, indicating a compensated metal without an open orbit. This result is consistent with the results of the dHvA experiment and 5f-itinerant hand calculation.

    DOI: 10.1143/JPSJ.68.972

    Web of Science

    researchmap

  • Pressure Effect on the Fermi Surface Properties of the Heavy Fermion Compound CeRu<SUB>2</SUB>Si<SUB>2</SUB>

    H.Aoki, M.Takashita, N.Kimura, C.Terakura, T.Terashima, S.Uji, T.Matsumoto, K.Maezawa, R.Settai, Y.Onuki

    Proceedings of 4<SUP>th</SUP> Int. Symposium on Advanced Physical Fields   37 - 40   1999年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Critical behavior of susceptibility at the nuclear ordering transition in PrCu6 査読

    K Akashi, K Kawabata, A Matsubara, O Ishikawa, T Hata, H Ishii, T Kodama, A Koyanagi, R Settai, Y Onuki

    PHYSICAL REVIEW LETTERS   82 ( 6 )   1297 - 1300   1999年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    The nuclear susceptibility and magnetization of a Van Vleck paramagnet PrCu6 have been measured through the nuclear ordering transition. At zero magnetic field, the susceptibility shows a critical behavior at the transition temperature of 2 mK. This critical behavior shrinks and disappears as the applied magnetic field is increased. It is found that this behavior of the susceptibility is consistent with the electrical resistivity anomaly near the transition in its frequency and magnetic field dependence. The magnetization in magnetic fields shows a ferromagnetic increase at the transition, which coincides with the resistivity decrease in the ordered state. [S0031-9007(98)08321-5].

    DOI: 10.1103/PhysRevLett.82.1297

    Web of Science

    researchmap

  • dHvA effect study of the metamagnetic transition in CeRu2Si2 under pressure 査読

    M Takashita, H Aoki, T Miura, C Terakura, S Uji, T Matsumoto, K Maezawa, R Settai, Y Onuki

    PHYSICA B-CONDENSED MATTER   259-61   1093 - 1094   1999年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have performed the de Haas-van Alphen effect study under high pressure for both the field ranges below and above the metamagnetic transition field (H-m) in CeRu2Si2. The effective masses below H-m decrease considerably with pressure as expected from various macroscopic measurements, whereas above H-m it is found that the effective mass for the large hole surface does not change substantially with pressure. The dHvA oscillations can be traced all the way from below to above H-m and it is found that the transition of the dHvA oscillations takes place in a narrower held range than the transition width of magnetization. (C) 1999 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(98)00914-4

    Web of Science

    researchmap

  • Metamagnetic-like anomaly in CeCu6 査読

    Y Aoki, T Namiki, TD Matsuda, H Sugawara, H Sato, R Settai, Y Onuki

    PHYSICA B-CONDENSED MATTER   259-61   28 - 29   1999年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The field dependences of specific heat C and magnetocaloric effect (MCE) Delta T/Delta B in CeCu6 have been measured to investigate the thermadynamical aspects of the weak metamagnetic-like anomaly (MA). Around 1.7 T both properties exhibit anomalous behaviors, which have close similarities with those in CeRu2Si2. This fact suggests that the quasiparticle density of states in CeCu6 has a faint peak structure near the Fermi level, which is superposed on the Kondo-resonance peak. (C) 1999 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(98)01165-X

    Web of Science

    researchmap

  • Metamagnetic transitions based on the quadrupole moment in RCu2 single crystals 査読

    K Sugiyama, M Nakashima, Y Yoshida, R Settai, T Takeuchi, K Kindo, Y Onuki

    PHYSICA B-CONDENSED MATTER   259-61   896 - 897   1999年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We studied the high-field magnetization in RCu2 (R = Ce, Pr, Nd, Sm, Dy, Tb and Ho) with the orthorhombic CeCu2-type crystal structure. The field-induced metamagnetic transition due to the switching of the different magnetic anisotropy states was observed in RCu2 (R = Ce, Pr, Dy and Tb). The origin of the transition is analyzed theoretically on the basis of the quadrupolar interaction and crystalline electric field. (C) 1999 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(98)00808-4

    Web of Science

    researchmap

  • de Haas-van Alphen effect in LaNi2Ge2 査読

    K Maezawa, S Sakane, T Fukuhara, H Ohkuni, R Settai, Y Onuki

    PHYSICA B-CONDENSED MATTER   259-61   1091 - 1092   1999年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The de Haas-van Alphen (dHvA) Effect of LaNi2Ge2, a reference material for a non-magnetic heavy electron compound CeNi2Ge2, has been investigated. Many branches with the frequencies from 26 MG to 120 MG have been observed. The angular dependence of the frequencies indicates a complicated Fermi surface which consists of a multi-connected surface. The cyclotron effective masses for each branch were also determined to be 1.2m(0)-2.7m(0). (C) 1999 Published by Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(98)00735-2

    Web of Science

    researchmap

  • Fermi surfaces of RPb3 査読

    D Aoki, Y Katayama, S Nojiri, R Settai, Y Inada, K Sugiyama, Y Onuki, H Harima, Z Kletowski

    PHYSICA B-CONDENSED MATTER   259-61   1083 - 1084   1999年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have observed the de Haas-van Alphen (dHvA) oscillations in SmPb3, GdPb3, EuPb3 and YbPb3. Detected dHvA branches are discussed on the basis of the result of the FLAPW band calculation. (C) 1999 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0921-4526(98)00938-7

    Web of Science

    researchmap

  • Antiferroquadrupolar ordering and Fermi surface property in PrPb3 査読

    D. Aoki, Y. Katayama, R. Settai, Y. Inada, Y. Onuki, H. Harima, Z. Kletowski, T. Tayama, T. Sakakibara

    Jpn. J. Appl. Phys.   11   188   1999年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    researchmap

  • De Haas-van Alphen effect of UB2, UB4 and UGa3 査読

    E. Yamamoto, T. Honma, Y. Haga, D. Aoki, M. Hedo, Y. Inada, R. Settai, H. Yamagami, Y. Onuki

    Jpn. J. Appl. Phys.   11   209   1999年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    researchmap

  • Magnetization Study of Superconductivityin UPt3 and CeRu2 査読

    K. Tenya, T. Tayama, H. Amitsuka, T. Sakakibara, N. Kimura, E. Yamamoto, Y. Haga, M. Hedo, K. Maezawa, Y. Inada, R. Settai, Y. Onuki

    JJAP Series   11   53   1999年

     詳細を見る

  • Fermi surface properties and de Haas–van Alphen oscillation in both the normal and superconducting mixed states of URu2Si2 査読

    H. Ohkuni, Y. Inada, Y. Tokiwa, K. Sakurai, R. Settai, T. Honma, Y. Haga, E. Yamamoto, Y. Ōnuki, H. Yamagami, S. Takahashi, T. Yanagisawa

    Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties   79 ( 7 )   1045 - 1077   1999年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We have succeeded in growing a high-quality single crystal of URu2Si2 with a residual resistivity ratio of 255 and performed magnetoresistance and de Haas–van Alphen (dHvA) experiments. The dHvA oscillations were observed clearly in both the normal and superconducting mixed states. From the magnetoresistance experiments, it is concluded that URu2Si2 is a compensated metal with equal carrier numbers of electrons and holes. In the dHvA experiments we observed three kinds of Fermi surfaces. We studied precisely the Fermi surface properties in both the normal and mixed states. The dHvA frequency does not change in magnitude between the normal and mixed states, while the cyclotron effective mass is reduced, and the corresponding Dingle temperature or scattering rate of the conduction electron increases in the mixed state. © 1999 Taylor and Francis Group, LLC.

    DOI: 10.1080/13642819908214859

    Scopus

    researchmap

  • deHaas-vanAlphen oscillations and magnetic properties of YbPb3 and EuPb3 査読

    D Aoki, Y Katayama, R Settai, N Suzuki, K Sugiyama, K Kindo, H Harima, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   67 ( 12 )   4251 - 4259   1998年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We observed the de Haas-van Alphen oscillations of a Pauli paramagnetic compound YbPb3 and an antiferromagnetic compound EuPb3. Detected Fermi surfaces in YbPb3 are three in number, which are well explained by the FLAPW band calculations. The cyclotron effective masses are in the range from 0.21 to 0.60 m(0). The paramagnetic and antiferromagnetic Fermi surfaces were detected in EuPb3. The former Fermi surface is the same as in YbPb3, which is seen by magnetic breakdown. EuPb3 is a divalent compound whose magnetic properties were studied by the specific heat, magnetic susceptibility and high-field magnetization experiments.

    DOI: 10.1143/JPSJ.67.4251

    Web of Science

    researchmap

  • Elastic anomalies and acoustic de Haas-van Alphen effects in Sr2RuO4 査読

    H Matsui, M Yamaguchi, Y Yoshida, A Mukai, R Settai, Y Onuki, H Takei, N Toyota

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   67 ( 11 )   3687 - 3690   1998年11月

     詳細を見る

    記述言語:英語   出版者・発行元:PHYSICAL SOC JAPAN  

    Ultrasound velocity measurements based on a phase comparison method for four different modes have been done on a copper-free layered perovskite superconductor Sr2RuO4 With T-c = 1.2 K. Anomalous softening is observed in the longitudinal C-11 and C-33 modes below 108 K, which is attributed to the coupling of the electronic states to the strain with Gamma(1) representation in the tetragonal point group D-4h The discontinuous change of the slope in C-11 and C-33 at Te is basically explained by the second-order strain dependence of T-c, partial derivative(2)T(c)/partial derivative epsilon(uk)(2). From the initial slope of the upper critical field H-c2, the anisotropy ratio in the coherence length is found to he 28, in agreement with previous ac susceptibility measurements. Acoustic de Haas-van Alphen oscillations for the cylindrical alpha-Fermi surface with 3.2m(0) are observed in C-33 as a function of the magnetic field applied perpendicular to the Q2D conducting plane. The area coefficient is evaluated to be \Lambda(zz)\ = 20+/-5 from the Kataoka-Goto model. The multiband term \Lambda(zz)(m)\ contributes dominantly to \Lambda(zz)\, which corresponds to the interband charge transfer.

    DOI: 10.1143/JPSJ.67.3687

    Web of Science

    researchmap

  • Electrodynamics of the superconducting state in CeRu2 査読

    H Matsui, T Yasuda, M Hedo, R Settai, Y Onuki, E Yamamoto, Y Haga, N Toyota

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   67 ( 10 )   3580 - 3584   1998年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We have studied the complex conductivity in superconducting and normal metallic slates of CeRu2 by the surface impedance measurements at millimeter-wave frequency of 45.4 GHz. The temperature dependence of the complex conductivity below T-c = 6.2 K exhibits the characteristic behaviors as seen in a conventional superconductor. The coherence peak observed in the real part al provides a strong evidence for a conventional s-wave superconductivity as well as the previous NQR measurements. The temperature dependence of the penetration depth evaluated from the surface reactance at low temperatures has revealed the ratio of 2 Delta(0)/k(B)T(c) = 4.4. The strong-coupling theories suggest the electron-phonon coupling strength with lambda(cp) &lt; 2. These results indicate that CeRu2 is an intermediate strong-coupling superconductor in a clean limit.

    DOI: 10.1143/JPSJ.67.3580

    Web of Science

    researchmap

  • High-field magnetization in TbCu2 and HoCu2 single crystals 査読

    K Sugiyama, M Nakashima, Y Yoshida, Y Kimura, K Kindo, T Takeuchi, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   67 ( 9 )   3244 - 3250   1998年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We measured the electrical resistivity, specific heat, magnetic susceptibility and high-field magnetization in TbCu2 with the orthorhombic structure. The metamagnetic transtion was found in a wide temperature range of 4.2 to 150 K for the magnetic field along the c-axis. This transition is similar to those of DyCu2 and PrCu2, which are due to the magnetic-axis conversion between easy (a-) and hard (c-) axes in magnetization. The metamagnetic transition was, however, not found in HoCu2 with the same crystal structure and similar magnetic anisotropy.

    DOI: 10.1143/JPSJ.67.3244

    Web of Science

    researchmap

  • High-temperature magnetic order in the singlet-ground-state compound PrCu2 査読

    A Schenck, D Andreica, FN Gygax, M Pinkpank, Y Onuki, P Ahmet, M Abliz, R Settai, A Amato, N Kaplan

    PHYSICAL REVIEW B   58 ( 9 )   5205 - 5208   1998年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    It is known that PrCu2 shows a modulated antiferromagnetic structure below T-N=(50-60) mK that is claimed to be of a cooperative nuclear-electronic nature [S. Kawarazaki and J. Arthur, J. Phys. Sec. Jpn. 51, 1077 (1988)]. Here we report on an observation by muon spin-rotation spectroscopy that this order seems to persist on a short-range scale with an apparently unchanged structure up to 60 K, i.e., up by three orders of magnitude as compared with T-N. We conjecture that the apparent magnetic order is of a secondary nature and the primary mechanism involves quadrupolar effects.

    DOI: 10.1103/PhysRevB.58.5205

    Web of Science

    researchmap

  • Single crystal growth and physical properties of U5Ge3 査読

    E Yamamoto, Y Haga, A Nakamura, Y Kimura, R Settai, Y Onuki

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   67 ( 8 )   2958 - 2959   1998年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    DOI: 10.1143/JPSJ.67.2958

    Web of Science

    researchmap

  • Oscillatory angular dependence of the magnetoresistance in Sr2RuO4 査読

    Y Yoshida, A Mukai, R Settai, Y Onuki, H Takei

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   67 ( 7 )   2551 - 2552   1998年7月

     詳細を見る