Faculty Profiles - SETTAI Rikio

Papers - SETTAI Rikio

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Fermi surface of the heavy-fermion superconductor (formula presented) Reviewed

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

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

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

Pressure-temperature phase diagram of antiferromagnetism and superconductivity in (formula presented) and (formula presented) (formula presented) study under pressure Reviewed

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

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

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

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

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

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

Evolution of pressure-induced heavy fermion state and superconductivity in (formula presented) A high-pressure Fermi surface study Reviewed

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

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

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

Magnetic and fermi surface properties of UCoGa5 and URhGa5 Reviewed

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

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

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

De haas-van alphen effect under pressure in UGe2 Reviewed

Rikio Settai, Yoshinori Haga, Miho Nakashima, Shugo Ikeda, Tomoyuki Okubo, Shingo Araki, Yoshichika Ōnuki

Journal of Nuclear Science and Technology 39 94 - 97 2002

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

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

Fermi surface study on uranium-based intermetallic compounds Reviewed

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

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

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

Single Crystal Growth and the High-pressure Effect of an Electronic State in UNiGa5 Reviewed

Miho Nakashima, Yoshihumi Tokiwa, Hirokazu Nakawaki, Yoshinori Haga, Yoshiya Uwatoko, Rikio Settai, Yoshichika Ōnuki

Journal of Nuclear Science and Technology 39 214 - 216 2002

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

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

An unusual hollow cylindrical Fermi surface of a quasi-two-dimensional compound CeAgSb2 Reviewed

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

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

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

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

Fermi surface instability in CeRh2Si2 under pressure

S. Araki, R. Settai, T. C. Kobayashi, H. Harima, Y. Onuki

Physical Review B - Condensed Matter and Materials Physics 64 ( 22 ) 2244171 - 2244177 2001.12

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

That the 4f electrons in the rare-earth antiferromagnetic compound CeRh2Si2 should be considered as localized electrons at cerium sites has been confirmed by comparing a de Haas-van Alphen experiment to the result of energy band calculations for LaRh2Si2. When pressure p is applied to the compound, the Néel temperature TNI=36 K decreases and finally becomes zero at pc≃1.0-1.1 GPa. The topology of the Fermi surface is found to be almost unchanged up to 1.0 GPa, but the cyclotron effective mass increases with increasing pressure. Above 1.1 GPa, the topology of the Fermi surface changes abruptly. A new Fermi surface is explained by the 4f-itinerant-band model. The corresponding cyclotron mass is large, being about 22m0.

Quasi-two dimensional Fermi surfaces in rare earth and uranium compounds: UX2, CeTIn5 and UTGa5 Reviewed

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 2001.10

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

Unconventional superconductivity in CeCoIn5 studied by the specific heat and magnetization measurements (vol 70, pg 2248, 2001) Reviewed

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 2001.10

Unconventional superconductivity in CeCoIn5 studied by the specific heat and magnetization measurements Reviewed

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 2001.8

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

Observation of large CP violation in the neutral B meson system Reviewed

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 ) 2001.8

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

Pressure-induced superconductivity in a ferromagnet UGe2 (vol 13, pg L17, 2001) Reviewed

N Tateiwa, TC Kobayashi, K Hanazono, K Amaya, Y Haga, R Settai, Y Onuki

JOURNAL OF PHYSICS-CONDENSED MATTER 13 ( 29 ) 6443 - 6443 2001.7

Angular position of nodes in the superconducting gap of quasi-2D heavy-fermion superconductor CeCoIn5 Reviewed

K Izawa, H Yamaguchi, Y Matsuda, H Shishido, R Settai, Y Onuki

PHYSICAL REVIEW LETTERS 87 ( 5 ) 2001.7

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

Quadrupolar phase diagram and Fermi surface properties in the localized 5f(2)-electron system UPd3 Reviewed

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 2001.6

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

Single crystal growth and de Haas-van Alphen effect of TmAl3 Reviewed

T Ebihara, D Aoki, Y Inada, R Settai, K Sugiyama, Y Haga, Y Onuki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 226 101 - 102 2001.5

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

Observation of heavy electrons in the filled skutterudite PrFe4P12 via the de Haas-van Alphen effect Reviewed

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 2001.5

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

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