Faculty Profiles - SETTAI Rikio

Papers - SETTAI Rikio

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

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

JAPANESE JOURNAL OF APPLIED PHYSICS 54 ( 4 ) 2015.4

Language：English Publishing type：Research paper (scientific journal) Publisher：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

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

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

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 84 ( 3 ) 2015.3

Language：English Publishing type：Research paper (scientific journal) Publisher：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

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Spontaneous Magnetization of Non-centrosymmetric Superconductor LaNiC2 Reviewed

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 ) 2015.1

Language：English Publishing type：Research paper (scientific journal) Publisher：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

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Single crystal growth and electronic state of UPd2Cd20 Reviewed

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

Language：English Publishing type：Research paper (international conference proceedings) Publisher：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

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

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

Language：English Publishing type：Research paper (international conference proceedings) Publisher：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

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

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

Language：English Publishing type：Research paper (international conference proceedings) Publisher：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

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

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

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

Language：English Publishing type：Research paper (international conference proceedings) Publisher：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

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Themal Expansion and Magnetostriction of YbAuCu<inf>4</inf> Reviewed

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

Physics Procedia 75 460 - 467 2015

Publishing type：Research paper (international conference proceedings)

© 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

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Themal Expansion and Magnetostriction of YbAuCu4 Reviewed

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

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

Language：English Publishing type：Research paper (international conference proceedings) Publisher：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

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

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

Physics Procedia 75 56 - 61 2015

Publishing type：Research paper (international conference proceedings)

© 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

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21aBB-4 In-NQR study of the magnetic structure in single crystals of CeRhIn_5

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

Meeting Abstracts of the Physical Society of Japan 70 1949 - 1949 2015

22aPS-42 Ce valence in the heavy fermion compound CeIrIn_5 at high magnetic fields

Matsuda Y. H., Terashima T., Settai R., Kawamura N., Mizumaki M., Inami T.

Meeting Abstracts of the Physical Society of Japan 70 2134 - 2134 2015

22aPS-55 X-ray absorption spectroscopy in YbIr_2Zn_<20> under high pressure

Honda F., Hirose Y., Mizumaki M., Kawamura N., Tsutsui S., Ishimatsu N., Watanuki T., Watanabe S., Aoki D., Settai R., Onuki Y.

Meeting Abstracts of the Physical Society of Japan 70 2147 - 2147 2015

22aPS-122 DC magnetic susceptibility measurements of Noncentrosymmetric Superconductor LaPt_3Si

Fujisawa T., Yamaguchi A., Sumiyama A., Kawakatsu D., Motoyama G., Takeuchi T., Settai R., Onuki Y.

Meeting Abstracts of the Physical Society of Japan 70 2211 - 2211 2015

22aPS-44 In-NQR study of heavy fermion superconductors CeIr(In_<1-x>Cd_x)_5 under pressure II

Yashima M., Tani K., Mukuda H., Kitaoka Y., Shishido H., Honda F., Settai R., Onuki Y.

Meeting Abstracts of the Physical Society of Japan 70 2136 - 2136 2015

22aPS-39 Electrical resistivity of CeIr(In_<1-x>Cd_x)_5 under pressure

Tsunoda R., Hirose Y., Honda F., Settai R., Onuki Y.

Meeting Abstracts of the Physical Society of Japan 70 2132 - 2132 2015

21pBB-10 Single crystal growth and electronic state of RPt_2Cd_<20> (R=Rare Earth)

Doto H., Hirose Y., Honda F., Li D. X., Aoki D., Takeuchi T., Haga Y., Settai R.

Meeting Abstracts of the Physical Society of Japan 70 2012 - 2012 2015

17aPS-25 De Haas-van Alphen effect under pressure in heavy fermion antiferromagnet CeAl_2 II

Sase Y., Hirose Y., Honda F., Aoki D., Settai R.

Meeting Abstracts of the Physical Society of Japan 70 1821 - 1821 2015

17aPS-18 Hall effect in CeRh_2Si_2 under high pressure

Araki S., Onji T., Kitagawa S., Kobayashi T. C., Miyazaki M., Settai R., Sakai H.

Meeting Abstracts of the Physical Society of Japan 70 1814 - 1814 2015

17aPS-58 High-field magnetization of PrPt_2Cd_<20>

Hirose Y., Doto H., Settai R., Takeuchi T., Honda F., Aoki D., Haga Y., Yoshizawa D., Kida T., Sugiyama K., Hagiwara M.

Meeting Abstracts of the Physical Society of Japan 70 1853 - 1853 2015

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