論文 - 辺土　正人

Effect of pressure on the electrical resistivity of CeCu2Si2

Koeda Masahito, Hedo Masato, Uwatoko Yoshiya, Matsumoto Takehiko, Takeda Naoya, Ishikawa Masayasu

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   272   E175 - E176   2004年05月 [ 査読有り ]

掲載種別: 研究論文（国際会議プロシーディングス）

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Design of micro pressure cell for measurements of specific heat and magnetization

Umehara I, Tomioka F, Tsuboi A, Ono T, Hedo M, Uwatoko Y

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   272   2301 - 2302   2004年05月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Pressure effect and temperature dependence of lattice constants for Ce(Ru_0.85Rh_0.15)₂Si₂

Koyama, K; Nakano, T; Hedo, M; Uwatoko, Y; Murayama, S

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS ( ELSEVIER SCIENCE BV )  272 ( 2 ) E109 - E110   2004年05月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

X-ray powder diffraction has been studied on Ce(Ru0.85Rh0.15)(2)Si-2 between 300 and 4 K under pressure up to 32 GPa with a diamond anvil cell, and the lattice constants and the bulk modulus have been obtained. The bulk modulus shows a rapid drop between 100 and 50 K; when the temperature decreases from 300 to 4 K: This tendency is most likely attributed to Kondo effect and/or a sign of a spin density wave. (C) 2003 Elsevier B. V. All rights reserved.

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Characterization of transport and magnetic properties of a Mott insulator, beta'-(BEDT-TTF)(2)IBrCI

Uchiyama K, Miyashita M, Taniguchi H, Satoh K, Mori N, Miyagawa K, Kanoda K, Hedo M, Uwatoko Y

JOURNAL DE PHYSIQUE IV   114   387 - 389   2004年04月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Characterization of transport and magnetic properties of a Mott insulator, beta'-(BEDT-TTF)(2)IBrCI

K Uchiyama, M Miyashita, H Taniguchi, K Satoh, N Mori, K Miyagawa, K Kanoda, M Hedo, Y Uwatoko

JOURNAL DE PHYSIQUE IV ( E D P SCIENCES )  114   387 - 389   2004年04月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

Physical properties of an organic conductor, beta'-(BEDT-TTF)(2)IBrCl, were characterized under ambient and extremely high pressures. Semiconducting behavior with activation energy, E-a=0.11eV, and antiferromagnetic transition with T-N=19.5K were uncovered in the present work. In addition, we have found that this salt showed a sign of superconductivity at 8.0GPa in common with the case of the beta'-(BEDT-TTF)(2)ICl2, which is the highest-T-c superconductor among organics.

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Fermi-liquid instability of CeRh₂Si₂ near a pressure-induced quantum phase transition -: art. no. 144428

Ohashi, M; Oomi, G; Koiwai, S; Hedo, M; Uwatoko, Y

PHYSICAL REVIEW B   68 ( 14 )   2003年10月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

The electrical resistivity of single crystalline CeRh2Si2 has been measured at high pressure up to 8 GPa, and low temperature down to 2.0 K for the current along the a and c axes. Two magnetic phase transitions TN1=35 K and TN2=24 K at ambient pressure were observed as a function of pressure. It is found that both transitions TN1 and TN2 are suppressed by applying pressure and disappear near the critical pressure at PC1∼1.0 GPa and PC2∼0.6 GPa, respectively. The transition for TN1 is second order and the one for TN2 is first order. The resistivity shows T2 dependence at low temperature in a wide pressure range from ambient pressure up to 8 GPa, indicating that a Fermi liquid state still exists near PC1 and PC2. According to the comparison between the coefficient of T2 term and the Sommerfeld coefficient γ, however, it is suggested that the enhancement of many-body dynamical effect occurs near the critical pressure PC1∼1.0 GPa. These results are discussed on the basis of the pressure-induced quantum phase transition. © 2003 The American Physical Society.

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Transport properties of the heavy-fermion superconductor Ce2CoIn8

Chen GF, Ohara S, Hedo M, Uwatoko Y, Sakamoto I

JOURNAL OF PHYSICS-CONDENSED MATTER   15 ( 28 ) S2175 - S2178   2003年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Electrical resistivity of single-crystal URhGe₂ under high pressure

Matsuda, TD; Ikeda, S; Haga, Y; Yamamoto, E; Hedo, M; Uwatoko, Y; Onuki, Y

JOURNAL OF PHYSICS-CONDENSED MATTER ( IOP PUBLISHING LTD )  15 ( 28 ) S2019 - S2021   2003年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

We have measured the electrical resistivity under pressure for the orthorhombic ferromagnet URhGe2. Its two ferromagnetic ordering temperatures T-C2 = 30 K and T-C1 = 25 K exhibit different pressure dependences. T-C2 increases under pressure from 30 K at ambient pressure to 40 K at 6-8 GPa, while T-C1 decreases with increasing pressure and seems to vanish at around 8 GPa. URhGe2 is found to be ferromagnetic even at 8 GPa, and the values of A and rho(0) in the electrical resistivity expression rho = rho(0) + AT(2) are unchanged against pressure.

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Design of 4GPa class hybrid high pressure cell for dilution refrigerator

Uwatoko Y, Hedo M, Kurita N, Koeda M, Abliz M, Matsumoto T

PHYSICA B-CONDENSED MATTER   329   1658 - 1659   2003年05月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Development of AC susceptibility technique under high pressure and its application to organic superconductor

Kurita A, Miyashita M, Taniguchi H, Satoh K, Tamura M, Kato R, Hedo M, Uwatoko Y

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   388   603 - 604   2003年05月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Pressure effect on Hall coefficient in multilayered high-T_c cuprates

Watanabe, T; Tokiwa, K; Moriguchi, M; Horike, R; Iyo, A; Tanaka, Y; Ihara, H; Ohashi, M; Hedo, M; Uwatoko, Y; Môri, N

JOURNAL OF LOW TEMPERATURE PHYSICS ( KLUWER ACADEMIC/PLENUM PUBL )  131 ( 3-4 ) 681 - 685   2003年05月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

Temperature dependence of the Hall coefficient and the resistivity in Tl2Ba2CaCu2Oy (Tl-2212),Tl2Ba2Ca2Cu3Oy (Tk-2223) and Cu0.7C0.3Ba2Ca3Cu4Oy (Cu-1234) have been measured under high pressure up to 6 GPa. The values of the intrinsic T-c enhancement not related to charge transfer by applied pressure were estimated to be similar to0.8K/GPa for the Tl system and similar to1.1K/GPa for Cu-1234.

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Field effect on itinerant electron magnetism of Y_1-<i>x</i>Er<i>_x</i>CO₂ compounds

Nakama, T; Tokumura, M; Uchima, K; Hedo, M; Uwatoko, Y; Yagasaki, K; Burkov, AT

PHYSICA B-CONDENSED MATTER ( Physica B: Condensed Matter )  329 ( II ) 952 - 954   2003年05月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

Thermopower S and electrical resistivity ρ of cubic Laves phase pseudo-binary compounds Y1-xErxCo2 were measured from 2 to 300 K in magnetic fields up to 15 T. S and ρ show a strong field dependence in a vicinity of the magnetic ordering temperature. The reduction of the exchange magnetic field Bexc acting on Co 3d electrons by Y substitution for Er results in a separation of magnetic transition temperatures of Er and Co subsystems in Y0.4Er 0.6Co2. The collapse of the itinerant Co 3d moments of Y0.4Er0.6Co2 is induced by applying external magnetic field about 10 T. © 2003 Elsevier Science B.V. All rights reserved.

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Possible superconductivity in metal(dmit)₂ Langmuir-Blodgett films

Miura, YF; Hedo, M; Uwatoko, Y; Saito, S; Sugi, M

SYNTHETIC METALS ( ELSEVIER SCIENCE SA )  137 ( 1-3 ) 1311 - 1312   2003年04月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

The resistance of the Langmuir-Blodgen films of ditetradecyldimethylammonium-Au(dmit)(2) has been measured under hydrostatic pressure up to 0.7 GPa. The room-temperature resistance decreases with increasing pressure and reaches a 0.6-times smaller value compared to that at ambient pressure. The film under the pressure shows a clear resistance decrease below 1.4 K on cooling, while that under ambient pressure shows a blunt decrease below 0.85 K and it turns to increase below 0.65 K. These results suggest the existence of the pressure-induced superconducting phase together with the earlier results of the ac magnetic susceptibility measurement.

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Superconductivity at 14.2 K in layered organics under extreme pressure

Taniguchi H, Miyashita M, Uchiyama K, Satoh K, Mori N, Okamoto H, Miyagawa K, Kanoda K, Hedo M, Uwatoko Y

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   72 ( 3 ) 468 - 471   2003年03月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Effect of pressure on electrical resistivity and lattice parameters of CeRh2Si2

Ohashi M, Oomi G, Koiwai S, Hedo M, Uwatoko Y

ACTA PHYSICA POLONICA B   34 ( 2 ) 1181 - 1184   2003年02月 [ 査読有り ]

掲載種別: 研究論文（国際会議プロシーディングス）

The restraint of valence transition in YbInCu4 by high pressure

Hedo M, Uwatoko Y, Matsumoto T, Sarrao JL, Thompson JD

ACTA PHYSICA POLONICA B   34 ( 2 ) 1193 - 1196   2003年02月 [ 査読有り ]

掲載種別: 研究論文（国際会議プロシーディングス）

Effect of pressure on the ferromagnetic cerium compound CeCu9Sn4

Y Ishii, N Mori, M Hedo, Y Uwatoko

ACTA PHYSICA POLONICA B ( ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS )  34 ( 2 ) 1249 - 1252   2003年02月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

Electrical resistivity measurements under hydrostatic pressure up to 2.2 GPa was carried out for a ferromagnetic ternary cerium compound CeCu9Sn4. The ferromagnetic transition temperature increases with increasing pressure up to 0.8 GPa and then decreases with increasing pressure above 1 GPa. Origins of this pressure dependence may be the competition between magnetic interaction in the c-plane and along the c-direction.

Pressure effect on antiferromagnetic ordering in UPb₃

Haga, Y; Yamamoto, E; Onuki, Y; Nakashima, M; Aoki, D; Onuki, Y; Hedo, M; Uwatoko, Y

ACTA PHYSICA POLONICA B   34 ( 2 ) 1239 - 1242   2003年02月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Pressure effect on antiferromagnetic ordering in UPb3

Y. Haga, E. Yamamoto, Y. Onuki, M. Nakashima, D. Aoki, M. Hedo, Y. Uwatoko

Acta Phys. Pol. B   34 ( 2 ) 1239   2003年02月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Effect of pressure on the ferromagnetic cerium compound CeCu₉Sn₄

Ishii, Y; Mori, N; Hedo, M; Uwatoko, Y

ACTA PHYSICA POLONICA B   34 ( 2 ) 1249 - 1252   2003年02月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）