Faculty Profiles - SETTAI Rikio

Papers - SETTAI Rikio

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Magnetization Study of Superconductivityin UPt3 and CeRu2 Reviewed

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

Fermi surface properties and de Haas–van Alphen oscillation in both the normal and superconducting mixed states of URu2Si2 Reviewed

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

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

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

deHaas-vanAlphen oscillations and magnetic properties of YbPb3 and EuPb3 Reviewed

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 1998.12

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

Elastic anomalies and acoustic de Haas-van Alphen effects in Sr2RuO4 Reviewed

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 1998.11

Language：English Publisher：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

Electrodynamics of the superconducting state in CeRu2 Reviewed

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 1998.10

Language：English Publishing type：Research paper (scientific journal) Publisher：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) < 2. These results indicate that CeRu2 is an intermediate strong-coupling superconductor in a clean limit.

DOI： 10.1143/JPSJ.67.3580

High-field magnetization in TbCu2 and HoCu2 single crystals Reviewed

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 1998.9

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

High-temperature magnetic order in the singlet-ground-state compound PrCu2 Reviewed

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 1998.9

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

Single crystal growth and physical properties of U5Ge3 Reviewed

E Yamamoto, Y Haga, A Nakamura, Y Kimura, R Settai, Y Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 67 ( 8 ) 2958 - 2959 1998.8

Oscillatory angular dependence of the magnetoresistance in Sr2RuO4 Reviewed

Y Yoshida, A Mukai, R Settai, Y Onuki, H Takei

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 67 ( 7 ) 2551 - 2552 1998.7

Magnetic and electrical properties of GdCu2 Reviewed

A Koyanagi, Y Yoshida, Y Kimura, R Settai, K Sugiyama, Y Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 67 ( 7 ) 2510 - 2513 1998.7

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

We measured the electrical resistivity, specific heat and de Haas-van Alphen (dHvA) oscillation of an antiferromagnetic compound GdCu2. The magnetic entropy, which was obtained from the specific heat, reaches Rln8 above 47 K, which is close to the Neel temperature of 40 K. The dHvA branches both in the antiferromagnetic state and the field-induced ferromagnetic state are highly different from those of a non-magnetic reference compound YCu2 or PrCu2. The Fermi surface in GdCu2 is most likely altered by the magnetic state.

DOI： 10.1143/JPSJ.67.2510

Metamagnetic transition based on the quadrupole moment in DyCu2 Reviewed

Y Yoshida, K Sugiyama, T Takeuchi, Y Kimura, D Aoki, M Kouzaki, R Settai, K Kindo, Y Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 67 ( 4 ) 1421 - 1430 1998.4

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

We have measured the electrical resistivity, magnetoresistance, specific heat; thermal expansion, de Haas-van Alphen effect, magnetic susceptibility and magnetization in DyCu2. The metamagnetic transtion has been observed in a wide temperature range from 1.3 to 170 K. The transition field decreases with increasing the temperature up to the Neel temperature of 27 K, while it increases linearly from about 50 K to 170 K. This metamagnetism is similar to that of PrCu2 and is explained on the basis of the quadrupole interaction.

DOI： 10.1143/JPSJ.67.1421

Magnetic investigation of binary U-Sn compounds Reviewed

SK Dhar, Y Kimura, M Kouzaki, K Sugiyama, R Settai, Y Onuki, T Takeuchi, K Kindo, P Manfrinetti

PHYSICA B 245 ( 3 ) 210 - 218 1998.3

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

We have investigated the magnetic properties of U5Sn4, USn, USn2 and U3Sn7. The first two compounds order ferromagnetically near 62 and 49 K, respectively. The magnetisation data indicate appreciable coercivity in these two materials, Two magnetic transitions occur in USn at 49 and 29 K, which may either be a signature of site-dependent magnetic behaviour of the symmetry-inequivalent U ions or a temperature-dependent realignment of all the U moments. USn2 and U3Sn7 undergo a transition to antiferromagnetic state near 80 K. (C) 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0921-4526(97)00882-X

Specific heat and phase diagram of NdCu2 in magnetic field Reviewed

S Takayanagi, H Sugawara, P Svoboda, R Settai, Y Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 67 ( 2 ) 594 - 598 1998.2

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

We have investigated the specific heat of NdCu2 at temperatures between 0.6 and 10 Ii in magnetic fields up to 6 T, applied along the three crystal axes of the orthorhombic structure. We have determined a magnetic phase diagram, in which more than seven phases have been identified for the field applied along the b-axis.

DOI： 10.1143/JPSJ.67.594

De Haas-van Alphen effect in RFe4P12 (R = La and Nd) Reviewed

H Sugawara, Y Abe, Y Aoki, H Sato, M Hedo, R Settai, Y Onuki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 177 359 - 360 1998.1

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

We report the first successful results on the de Haas-van Alphen (dHvA) experiments of the superconducting LaFe4P12 and the ferromagnetic NdFe4P12. Their Fermi surfaces are found to be similar except for the splitting of the dHvA branches for NdFe4P12 due to the ferromagnetic exchange interaction. (C) 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0304-8853(97)00481-2

Thermal properties of metamagnetic transition in heavy-fermion systems Reviewed

Y Aoki, TD Matsuda, H Sugawara, H Sato, H Ohkuni, R Settai, Y Onuki, E Yamamoto, Y Haga, AV Andreev, Sechovsky, V, L Havela, H Ikeda, K Miyake

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 177 271 - 276 1998.1

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

In order to investigate the metamagnetic anomaly (MA) observed in several heavy-fermion compounds, field dependence of specific heat C(B) and magnetocaloric effect have been measured in the prototypical 4f-electron compound CeRu(2)Si(2), and compared to that of a 5f-electron metamagnet UCoAl. In the C/T versus B curves, an unexpected double-peak structure is found in CeRu(2)Si(2), suggesting that MA is closely related to a sharp peak in the density of states of the hybridized quasiparticle bands. On the other hand, for UCoAl, only a small decrease in C/T is observed, although both compounds exhibit similar bulk magnetic properties. (C) 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0304-8853(97)00484-8

dHvA effect of CeRu2Si2 under pressure Reviewed

M Takashita, H Aoki, CJ Haworth, T Matsumoto, T Terashima, S Uji, C Terakura, T Miura, K Maezawa, R Settai, Y Onuki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 177 417 - 418 1998.1

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

We report pressure dependence of the Fermi surfaces (FSs) in CeRu2Si2 below and above the metamagnetic transition field (H-m). Below H-m, the dHvA frequencies arising from hole FSs decrease by 20% on application of 6 kbar, while that from an electron FS increases by 10%. The pressure dependence of the frequencies above H-m is much larger than that below H-m. The results are discussed in comparison with those of ferromagnetic reference material CeRu2Ge2. (C) 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0304-8853(97)00387-9

Metamagnetism based on the quadrupolar interaction in RCu2 Reviewed

K Sugiyama, Y Yoshida, A Koyanagi, R Settai, T Takeuchi, K Kindo, Y Onuki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 177 361 - 362 1998.1

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

High-field magnetization measurements in single crystalline CeCu2, TbCu2 and DyCu2 with the orthorhombic CeCu2-type crystal structure have been carried out. A field-induced metamagnetic transition for the magnetic field along the c-axis is observed, which is caused by the switching of the different magnetic anisotropy states. The origin of the transition is discussed on the basis of the quadrupolar interaction and crystalline electric field. (C) 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0304-8853(97)00934-7

De Haas-van Alphen effect and the antiferroquadrupolar ordering of PrPb3 Reviewed

D Aoki, Y Katayama, R Settai, Y Inada, Y Onuki, H Harima, Z Kletowski

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 177 365 - 366 1998.1

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

We have determined the Fermi surface properties of PrPb3 by a de Haas-van Alphen experiment. The cyclotron effective mass is extremely temperature dependent and highly anisotropic even for almost spherical Fermi surfaces, which is due to the antiferroquadrupolar ordering. (C) 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0304-8853(97)00931-1

de Haas-van Alptnen Effect off Strongly Correlated f-Electron Systems under Pressure Reviewed

M. Takashita, M. Takashita, H. Aoki, C. J. Haworth, T. Terashima, S. Uji, C. Terakura, T. Matsumoto, A. Uesawa, T. Suzuki, N. Sato, S. Kunii, R. Settai, Y. Onuki, T. Nishigaki, H. Sugawara, Y. Aoki, H. Sato

Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu 7 456 - 458 1998

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

We have studied the de Haas-van Alphen (dHvA) effect under pressure for some typical compounds of strongly correlated Ce compounds CeSb, CeB6, CeRu2Si2, CeRu2Ge2 and CeCo2. The pressure dependence of the dHvA frequencies is much larger than that expected from compressibility or that of normal metals. The pressure dependence of the effective masses have been measured in CeSb and CeB6, and it is difficult to explain that in terms of the increase of mixing with pressure. [de Haas-van Alphen effect, CeSb, CeB6, CeRu2Si2, CeCo2]. © 1998, The Japan Society of High Pressure Science and Technology. All rights reserved.

DOI： 10.4131/jshpreview.7.456

Neutron scattering study of the magnetic structure of DyCu2 Reviewed

Y Koike, N Metoki, Y Morii, Y Yoshida, R Settai, Y Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 66 ( 12 ) 4053 - 4054 1997.12

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