Faculty Profiles - SETTAI Rikio

Papers - SETTAI Rikio

Division display 341 - 360 of about 428 ／ All the affair displays >>

High-quality single-crystal growth and a change of the electronic states under pressure in CeRh2Si2 Reviewed

S Araki, R Settai, TC Kobayashi, Y Onuki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 226 80 - 82 2001.5

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

Pressure effects of susceptibility and specific heat in PrCu2 Reviewed

T Naka, J Tang, P Ahmet, R Settai, Y Onuki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 226 1008 - 1010 2001.5

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

Superconducting gap structure of spin-triplet superconductor Sr2RuO4 studied by thermal conductivity Reviewed

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 2001.3

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

Ultrasonic studies of the spin-triplet order parameter and the collective mode in Sr2RuO4 Reviewed

H Matsui, Y Yoshida, A Mukai, R Settai, Y Onuki, H Takei, N Kimura, H Aoki, N Toyota

PHYSICAL REVIEW B 63 ( 6 ) 2001.2

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

Shubnikov-de Haas effect study of cylindrical Fermi surfaces in UP2 Reviewed

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 2001.1

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

Pressure-induced superconductivity in a ferromagnet UGe2 Reviewed

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

JOURNAL OF PHYSICS-CONDENSED MATTER 13 ( 1 ) L17 - L23 2001.1

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

Ultrasonic studies of the spin-triplet order parameter and the collective mode in Sr2RuO4 Reviewed

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

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

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

Acoustic de Haas-van Alphen effect and elastic anomaly of transverse mode (C-11- C-12)/2 in Sr2RuO4 Reviewed

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 2000.12

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

The Fermi surface in filled skutterudite RFe4P12 (R=La and Nd) Reviewed

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 2000.9

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

Bulk 4f electronic states of Ce-based heavy fermion system probed by high-resolution resonance photoemission Reviewed

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 2000.9

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

Fermi surface properties of the enhanced Pauli paramagnet UAl3 Reviewed

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 2000.8

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

Magnetic domain structure in a hyperfine-enhanced nuclear magnet PrCu6 Reviewed

H Inaba, K Kawasaki, A Matsubara, O Ishikawa, T Hata, T Kodama, A Koyanagi, R Settai, Y Onuki

PHYSICA B 284 1692 - 1693 2000.7

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

DHvA oscillation in the anisotropic superconductors of UPd2Al3 and URu2Si2 Reviewed

Y Inada, Y Haga, H Ohkuni, Y Tokiwa, R Settai, T Honma, E Yamamoto, Y Onuki

PHYSICA B 284 523 - 524 2000.7

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

High-field magnetization and thermal expansion of UPd3 Reviewed

T Takeuchi, Y Tokiwa, K Sugiyama, R Settai, Y Haga, E Yamamoto, T Honma, K Kindo, Y Onuki

PHYSICA B 284 1285 - 1286 2000.7

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

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 2000.6

Pressure effect on the cooperative Jahn-Teller transition in PrCu2 Reviewed

S Takayanagi, H Tatta, A Miyashita, R Settai, Y Onuki, N Mori

PHYSICA B 281 583 - 585 2000.6

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

Hall effect and thermoelectric power in CeCu5.9Au0.1 and CeCu6 Reviewed

T Namiki, H Sato, J Urakawa, H Sugawara, Y Aoki, R Settai, Y Onuki

PHYSICA B 281 359 - 360 2000.6

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

Single-crystal growth by flux method and Fermi surface of uranium compounds Reviewed

D Aoki, P Wisniewski, K Miyake, R Settai, Y Inada, K Sugiyama, E Yamamoto, Y Haga, Y Onuki

PHYSICA B 281 761 - 763 2000.6

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

Electrodynamic response at metamagnetic anomaly in CeRu2Si2 Reviewed

H Matsui, T Yasuda, A Misawa, R Settai, E Yamamoto, Y Haga, Y Onuki, N Toyota

PHYSICA B-CONDENSED MATTER 281 56 - 58 2000.6

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

Metamagnetic transition of CeRh2Si2 under high fields and high pressures at various temperatures Reviewed

T Hamamoto, K Kindo, TC Kobayashi, Y Uwatoko, S Araki, R Settai, Y Onuki

PHYSICA B 281 64 - 65 2000.6

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

　 PREV - NEXT 　

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22