研究者詳細 - 摂待　力生

MISC - 摂待　力生

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Magnetic structure and crystal field excitation in heavy fermion superconductor CePt3Si

N Metoki, K Kaneko, TD Matsuda, A Galatanu, T Takeuchi, S Hashimoto, T Ueda, R Settai, Y Onuki, N Bernhoeft

PHYSICA B-CONDENSED MATTER 359 383 - 385 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

CePt3Si shows an antiferromagnetic order at T-N = 2.2 K and enters into a heavy fermion superconducting state at T-c approximate to 0.75K. We observed the appearance of clear antiferromagnetic reflections with Q(0) = (001/2) below TN. The observed antiferromagnetic peak exists even below T-SC, namely, the superconductivity coexists with-antiferromagnetic order in CePt3Si. The magnetic moments of 0.16(1)mu(B)/Ce lying in the basal plane order ferromagnetically in the c-plane with inversion center, and are stacked antiferromagnetically along the c-axis with lack of inversion symmetry. Clear crystal field excitations were observed at 1 and 24 meV. The magnetic susceptibility was consistent with the level scheme assuming the Gamma(7)(0MeV) - Gamma(6)(1.0meV) - Gamma(7)(24 meV). (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.070

Fermi surface properties of CePt3Si and LaPt3Si

Y Onuki, T Yasuda, H Shishido, S Hashimoto, T Ueda, R Settai, TD Matsuda, Y Haga, H Harima

PHYSICA B-CONDENSED MATTER 359 368 - 370 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

The topology of the Fermi surface in CePt3Si is Most likely similar to that in LaPt3Si. In fact, one small Fermi surface in CePt3Si is the same as that in LaPt3Si, where the main Fermi surface in LaPt3Si consists of three-dimensional multiply-connected Fermi surfaces. With increasing pressure, the topology of the Fermi surface in CePt3Si is approximately unchanged but the cyclotron effective mass is found to be reduced, together with a steep decrease of the Neel temperature and superconducting transition temperature. These results indicate that the heavy fermion state in CePt3Si, which is closely correlated with superconductivity, is stable at ambient pressure. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.063

de Haas-van Alphen effect in CeIn3 under pressure

R Settai, T Kubo, H Shishido, TC Kobayashi, Y Onuki

PHYSICA B-CONDENSED MATTER 359 317 - 319 2005年4月

記述言語：英語出版者・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 2.72 GPa for the magnetic field along [1 1 0]. A main Fermi surface with the dHvA frequency F = 9.4 x 10(7) Oe and a large cyclotron mass m(c)(*) = 53m(0) was observed at 2.72 GPa in the vicinity of the critical pressure where the Neel temperature is suppressed to zero. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.119

A drastic change of the Fermi surface at a critical pressure in CeRhIn 5: dHvA study under pressure

Hiroaki Shishido, Rikio Settai, Hisatomo Harima, Yoshichika Onuki

Journal of the Physical Society of Japan 74 ( 4 ) 1103 - 1106 2005年4月

記述言語：英語

We carried out the de Haas-van Alphen (dHvA) experiment for an antiferromagnet CeRhIn5 at high pressures up to 3 GPa. The cross-sectional areas of the Fermi surfaces due to main dHvA branches αi and β2 at ambient pressure, which are well explained by two kinds of nearly cylindrical Fermi surfaces of a non-4f reference compound LaRhIn5, are unchanged up to about 2.3 GPa, while the corresponding cyclotron masses mc* increase steeply above a pressure P* = 1.6 GPa where pressure-induced superconductivity sets in : mc* = 5.5 m0 at ambient pressure, 20 m0 at 1.6 GPa and 60 m0 at 2.2 GPa for branch β2, for example. Above 2.4 GPa, new dHvA branches appear, which are in good agreement with the corresponding dHvA branches of a 4f-itinerant heavy fermion superconductor CeCoIn5, indicating that the 4f electron of CeRhIn5 becomes itinerant and significantly contributes to the volume of the Fermi surface. The 4f-electron character is thus changed from localized to itinerant at a critical pressure Pc ≃ 2:35 GPa, where the superconducting transition temperature becomes a maximum. ©2005 The Physical Society of Japan.

DOI： 10.1143/JPSJ.74.1103

Fermi surface of LaRu4P12: A clue to the origin of the metal-insulator transition in PrRu4P12

Saha, SR, H Sugawara, Y Aoki, H Sato, Y Inada, H Shishido, R Settai, Y Onuki, H Harima

PHYSICAL REVIEW B 71 ( 13 ) 2005年4月

記述言語：英語出版者・発行元：AMER PHYSICAL SOC

We report the de Haas-van Alphen (dHvA) effect and magnetoresistance in the filled-skutterudite superconductor LaRu4P12, which is a reference material of PrRu4P12 that exhibits a metal-insulator (M-I) transition at T-MI similar or equal to 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 PrRu4P12. Observed cyclotron effective masses of (2.6-11.8)m(0), which are roughly twice the calculated masses, indicate the large mass enhancement even in the La-skutterudites. Comparing the FS between LaRu4P12 and PrRu4P12, an essential role of c-f hybridization cooperating with the FS nesting in driving the M-I transition in PrRu4P12 is clarified.

DOI： 10.1103/PhysRevB.71.132502

Unconventional superconductivity near the antiferromagnetic criticality in CeCoIn5 : a study of In-115-NQR under pressure

M Yashima, S Kawasaki, Y Kawasaki, GQ Zheng, Y Kitaoka, H Shishido, R Settai, Y Haga, Y Onuki

PHYSICA B-CONDENSED MATTER 359 404 - 406 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We report on a systematic evolution of the superconducting (SC) characteristics of CeCoIn5 via nuclear-quadrupole-resonance (NQR) measurement under pressure (P). The application of P significantly suppresses the nuclear spin-lattice relaxation rate 1/T-1 that is dominated by antiferromagnetic (AFM) spin fluctuations (SFs). The marked suppression of AFM SFs leads to the reduction in the size of SC energy gap. Nevertheless, T-c increases with the pressure due to the increase in HF bandwidth. This is expected to make the lifetime of quasi-particles sufficiently long. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.080

Field-angle-dependent specific heat in the unconventional heavy-fermion superconductor CeCoIn5

H Aoki, T Sakakibara, H Shishido, R Settai, Y Onuki, P Miranovic, K Machida

PHYSICA B-CONDENSED MATTER 359 410 - 412 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We have measured the field-angle-dependent specific heat, C(H,theta), in the unconventional heavy-fermion superconductor CeCoIn5 down to similar to 0.29K. In a magnetic field rotating in the tetragonal c-plane, a clear fourfold angular oscillation is observed in C(H,theta) with the minima (maxima) occurring along the [100] ([110]) directions. Oscillation persists down to low fields H << H-c2 thus directly proving the existence of gap nodes. Position of the minima in C(H,theta) indicates that the gap node is located along the [100] and [010] directions, implying that the superconducting gap symmetry of CeCoIn5 is most probably of d(xy) type. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.082

In-115-NQR study of antiferromagnetism and superconductivity near magnetic criticality in CeIn3

S Kawasaki, T Mito, Y Kawasaki, H Kotegawa, GQ Zheng, Y Kitaoka, H Shishido, S Araki, R Settai, Y Onuki

PHYSICA B-CONDENSED MATTER 359 413 - 415 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We report the discovery of novel phases in CeIn3 on the verge of antiferromagnetism (AFM) through the In-nuclear quadrupole resonance (NQR) measurements. We have found that even though a pressure (P)-induced phase separation into AFM and paramagnetism (PM) takes place, a novel superconductivity (SC), which is induced without strong spin fluctuations, has been found to coexist with AFM on a microscopic level. We propose that the magnetic excitations such as spin-density fluctuations induced by the first-order magnetic phase transition might mediate attractive interaction to form Cooper pairs. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.083

De Haas-van Alphen effect in the filled skutterudite SmFe4P12

D Kikuchi, M Kobayashi, H Sugawara, Y Aoki, H Sato, H Shishido, R Settai, Y Onuki

PHYSICA B-CONDENSED MATTER 359 874 - 876 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We have succeeded in growing high-quality single crystals and observing the de Haas-van Alphen (dHvA) effect in the filled skutterudite SmFe4P12. The Fermi surface topology of SmFe4P12 inferred from the dHvA experiment is similar to that of LaFe4P12, suggesting the localized character of 4f-electrons in SmFe4P12. The cyclotron effective mass enhanced to 4.3-9.2 m(0) indicates strong electron correlation in this compound. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.329

De Haas-van Alphen effect in PrFe4P12 under high pressure

H Sugawara, D Kikuchi, M Kobayashi, Y Aoki, H Sato, H Shishido, R Settai, Y Onuki

PHYSICA B-CONDENSED MATTER 359 880 - 882 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We have measured the de Haas-van Alphen (dHvA) effect in PrFe4P12 under high pressures up to 3.0 GPa, and found that both the dHvA frequency and cyclotron mass of psi-branch considerably decrease with increasing pressure. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.332

Pressure-induced superconductivity in UIr without inversion symmetry

T Akazawa, H Hidaka, H Kotegawa, TC Kobayashi, T Fujiwara, E Yamamoto, Y Haga, R Settai, Y Onuki

PHYSICA B-CONDENSED MATTER 359 1138 - 1140 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

Pressure-induced superconductivity is found in UIr without inversion symmetry. The pressure-temperature phase diagram has been investigated by means of electrical resistivity and magnetization. The phase diagram consists of two ferromagnetic phases. The ferromagnetic phase FM1 with T-Cl similar to 46 K at ambient pressure disappears around 1.7 GPa. With further increase of pressure, the phase (FM2) with small ferromagnetic moment appears in the pressure range of P-Cl < P < 2.6 GPa. The superconducting phase exists near the disappearance point of the FM2 phase, indicating that the superconductivity is associated with the ferromagnetic critical fluctuation around P-C2. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.335

Magnetic properties and B-T phase diagram in the heavy-fermion superconductor CePt3Si

T Takeuchi, M Shiimoto, H Kohara, S Hashimoto, T Yasuda, TD Matsuda, Y Haga, R Settai, Y Onuki

PHYSICA B-CONDENSED MATTER 359 380 - 382 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

Magnetic and superconducting properties have been investigated on a single crystal Of CePt3Si which is the recently discovered heavy-fermion superconductor. The effect of magnetic field on the antiferromagnetic transition temperature T-N was studied by the iso-field thermal expansion coefficient. From these results, together with the results of the electrical resistivity under magnetic fields, magnetostriction and magnetization measurements, we have constructed the magnetic and superconducting phase diagrams for H parallel to [110] and [001] (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.069

CEF-scheme of a semimetal Ce3Sn7

Y Okuda, T Yamamoto, D Honda, H Shishido, A Galatanu, Y Haga, TD Matsuda, T Takeuchi, K Kindo, K Sugiyama, R Settai, Y Onuki

PHYSICA B-CONDENSED MATTER 359 323 - 325 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We measured the magnetic susceptibility and magnetization 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 under the assumption that two Cc atoms in the 2(a) site possess a magnetic moment of 0.36 mu(B)/Ce and one Ce atom in the 4(i) site possesses no magnetic moment as in a valence fluctuating compound CeSn3, which was previously proposed by Bonnet et al. Furthermore, we carried out the de Haas-van Alphen experiment. The detected Fermi surfaces are many in number but are extremely small in volume, indicating that Ce3Sn7 is a semimetal. (c) 2005 Published by Elsevier B.V.

DOI： 10.1016/j.physb.2005.01.121

High-pressure effect on the electrical resistivity in CeNiGe3 and CeNi2Al5

M Nakashima, K Tabata, A Thamizhavel, TC Kobayashi, M Hedo, Y Uwatoko, K Shimizu, R Settai, Y Onuki

PHYSICA B-CONDENSED MATTER 359 266 - 268 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We have measured the electrical resistivity of antiferromagnetic Kondo compounds CeNiGe3 and CeNi2Al5 under pressure. In CeNiGe3, Neel temperature T-N initially increases with increasing pressure P up to 3 GPa, then decreases rather steeply with further increasing pressure, and becomes zero at a critical pressure P-c similar or equal to 5.5 GPa. The A and rho(0) values of the resistivity rho = rho(0) + AT(2) in the Fermi liquid relation become maximum around P-c. Superconductivity is found below 0.48 K in a wide pressure region from 4 to 10 GPa. In CeNi2Al5, the similar pressure dependence of TN is found, has a maximum at 3.9 GPa, and becomes zero around 6 GPa. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/i.physb.2005.01.066

de Haas-van Alphen effect in CeRhIn5 under pressure

H Shishido, R Settai, S Hashimoto, T Kubo, H Harima, Y Onukia

PHYSICA B-CONDENSED MATTER 359 184 - 186 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We have carried out the de Haas-van Alphen (dHvA) experiment of an antiferromagnet CeRhIn5 under pressure. The detected dHvA branches alpha(i) (i = 1, 2,3) and beta(2) at ambient pressure are well explained by the corresponding dHvA branches in LaRhIn5, indicating that the f electron is localized at ambient pressure. At 2.9 GPa, where the antiferromagnetic ordering disappears completely, a new branch alpha(i) (i = 1, 2, 3) appears. This is approximately the same as that of 4f-itinerant Fermi surface in CeCoIn5, suggesting that the 4f electronic state is changed into an itinerant one. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.030

Field-induced magnetic-axis conversion in TmCu2

K Sugiyama, T Yamamoto, K Sasaki, R Settai, T Takeuchi, K Kindo, Y Onuki

PHYSICA B-CONDENSED MATTER 359 214 - 216 2005年4月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

The metamagnetic transition was observed for H//a-axis at H-M = 33 T at 4.2 K in TmCu2 with the orthorhombic crystal structure. The magnetization for H//a, M-a changes into M-c after the metamagnetic transition. We confirmed by measuring the magnetostriction that the present field-induced magnetic-axis conversion is related to the quadrupole moment O-2(2) and induces expansion along the c-axis and shrinkage along the a-axis. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.040

25aPS-65 CePtAlの単結晶育成と高圧下電気抵抗(領域8ポスターセッション(f電子系等),領域8(強相関系:高温超伝導,強相関f電子系など))

植田泰輝, 中島美帆, 中島弘, Thaniizhavel Arumugam, 辺土正人, 上床美也, 松田達磨, 芳賀芳範, Kindo K, Settai R, 大貫惇睦

日本物理学会講演概要集 60 ( 1 ) 537 - 537 2005年3月

24pTA-14 重い電子系超伝導物質CePt_3Siの熱電対を用いた高圧下比熱測定(重い電子超伝導(Ce115系,CePt_3Si),領域8(強相関系:高温超伝導,強相関f電子系など))

立岩尚之, 芳賀芳範, 松田達磨, 池田修悟, 植田泰輝, 安田敬, 竹内徹也, 摂待力生, 大貫惇陸

日本物理学会講演概要集 60 ( 1 ) 497 - 497 2005年3月

25aPS-6 強磁性圧力誘起超伝導体UIrの純良単結晶育成と物性測定(領域8ポスターセッション(f電子系等),領域8(強相関系:高温超伝導,強相関f電子系など))

山本悦嗣, 芳賀芳範, 池田修悟, 松田達磨, 立岩尚之, 摂待力生, 大貫惇睦

日本物理学会講演概要集 60 ( 1 ) 523 - 523 2005年3月

25aPS-12 ThTIn_5(T:遷移金属)の単結晶育成と物性(領域8ポスターセッション(f電子系等),領域8(強相関系:高温超伝導,強相関f電子系など))

松田達磨, 芳賀芳範, 池田修悟, 摂待力生, 大貫惇睦

日本物理学会講演概要集 60 ( 1 ) 525 - 525 2005年3月

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