研究者詳細 - 小山　佳一

論文 - 小山　佳一

分割表示 487 件中 241 - 260 件目／全件表示 >>

M. Matsukawa, A. Tamura, S. Nimori, R. Suryanarayanan, T. Kumagai, Y. Nakanishi, M. Apostu, A. Revcolevschi, K. Koyama, N. Kobayashi . Anomalous pressure effect on the remanent lattice striction of a (La,Pr)(1.2)Sr1.8Mn2O7 bilayered manganite single crystal . PHYSICAL REVIEW B75 ( 1 ) 2007年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMERICAN PHYSICAL SOC

We have studied the pressure effect on magnetostriction, both in the ab plane and along the c axis of a (La, Pr)(1.2)Sr1.8Mn2O7 bilayered manganite single crystal over the temperature region where the field-induced ferromagnetic metal (FMM) transition takes place. For comparison, we have also examined the pressure dependence of magnetization curves at the corresponding temperatures. The applied pressure reduces the critical field of the FMM transition and it enhances the remanent magnetostriction. An anomalous pressure effect on the remanent lattice relaxation is observed and is similar to the pressure effect on the remanent magnetization along the c axis. These findings are understood from the viewpoint that the double-exchange interaction-driven FMM state is strengthened by the application of pressure.

DOI： 10.1103/PhysRevB.75.014427

Web of Science

Scopus

M. Kimata, Y. Oshima, H. Ohta, K. Koyama, M. Motokawa, H. M. Yamamoto, R. Kato . Low-temperature Fermi surface of the organic conductor β″ -(BEDT-TTF) (TCNQ)(1-x) (F1-TCNQ)x (x=0,0.05) from magnetooptical measurements . Physical Review B - Condensed Matter and Materials Physics75 ( 4 ) 2007年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

Magnetooptical measurements have been performed on the organic conductor β″ -(BEDT-TTF)(TCNQ) (x=0 salt), and a related compound, β″ -(BEDT-TTF)(TCNQ) 0.95 (F1-TCNQ) 0.05 (x=0.05 salt), to investigate their low-temperature Fermi surfaces (FSs). Although the room-temperature FS of both salts can be considered the same, our results indicate that the low-temperature FSs are completely different from each other. In the x=0 salt, the low-temperature FS consists of two very anisotropic quasi-two-dimensional (Q2D) FSs. Cross-sectional areas of anisotropic Q2D-FSs are very small, and correspond to 1-2 % of the first Brillouin zone at room temperature. On the other hand, in the x=0.05 salt, only a pair of quasi-one-dimensional FSs exist at low temperature. Compared with the band calculation of x=0 salt, this Q1D-FS originates from the BEDT-TTF conducting layers. This result indicates that the two hump-like anomalies in the temperature dependence of resistivity at 80 and 20 K, which are observed only in the x=0 salt, are related to the nesting of BEDT-TTF Q1D-FS. Hence, it is considered that anisotropic Q2D-FS pockets observed in the x=0 salt are generated by the imperfect nesting of Q1D-FS, and the density wave state may be formed in the x=0 salt at low temperatures. © 2007 The American Physical Society.

DOI： 10.1103/PhysRevB.75.045126

Web of Science

Scopus

Alexander V. Andreev, Keiichi Koyama, Nikolai V. Mushnikov, Vladimir Sechovsky, Yoshinobu Shiokawa, Isamu Satoh, Kazuo Watanabe . Transition from ferromagnetism to metamagnetism under pressure in a uo.94yo.o6coal single crystal . Journal of the Physical Society of Japan76 43 - 46 2007年1月査読

記述言語：英語掲載種別：研究論文（学術雑誌）

Substitution of Y for U in the itinerant 5f-electron metamagnet UCoAl transforms the system to a ferromagnetic ground state. Application of external hydrostatic pressure above 0.3 GPa suppresses the ferromagnetism and restores the "UCoAl-type" metamagnetism. However, the metamagnetic transition becomes of the second-order type instead of the first-order one for the parent UCoAl. © 2007 The Physical Society of Japan.

DOI： 10.1143/JPSJS.76SA.43

Web of Science

Scopus

Evgeniya A. Tereshina, Hajime Yoshida, Alexander V. Andreev, Irina S. Tereshina, Keiichi Koyama, Takeshi Kanomata . Magnetism of a Lu<inf>2</inf>Fe<inf>17</inf>H single crystal under pressure . Journal of the Physical Society of Japan76 82 - 83 2007年1月査読

記述言語：英語掲載種別：研究論文（学術雑誌）

Lu2Fe17 is a ferromagnet below TC∼140 K and antiferromagnet up to TN=275 K. Hydrogen absorption leads to a stabilization of the ferromagnetism over the whole range of magnetic order and to an increase of the ordering temperature up to TC=354 K in Lu 2Fe17H. The external pressure compensates the lattice expansion upon hydrogenation, and a reentrance of antiferromagnetism is observed. © 2007 The Physical Society of Japan.

DOI： 10.1143/JPSJS.76SA.82

Web of Science

Scopus

A.V. Andreev, K. Koyama, N.M. Mushnikov, V. Sechovsky, Y. Shiokawa, I. Satoh, and K. Watanabe . Interplay between effects of external pressure and dilution of the U-sublattice in UCoAl-base materials . J. Alloys Comp.441 33 - 38 2007年査読

K. Koyama, S. Miura, H. Okada, T. Shigeoka, K. Watanabe . Magnetic entropy changes of SmMn2Ge2 under high pressure . Mater. Trans.48 451 - 454 2007年査読

M. Matsukawa, A. Tamura, S. Nimmori, R. Suryanarayanan, T. Kumagai, Y. Nakanishi, M. Apostu, A. Revcolevschi, K. Koyama, and N. Kobayashi . Anomalous pressure effect on the remanent lattice striction of a (La, Pr)1.2Sr1.8Mn2O7 bilayered manganite single crystal . Phys. Rev. B75 14427 2007年査読

K. Hachitani, H. Amanuma, H. Fukazawa, Y. Kohori I. Watanabe, K. Koyama, K. Kumagai, C. Sekine and I. Shirotani . Sm-based filled Skutterudite phosphides SmT4P12 (T=Fe, Ru, Os) studied by 31P-NMR and μSR . J. Phys. Chem. Solid68 2080 - 2083 2007年査読

M. Matsukawa, Y. Yamato, T. Kumagai, A. Tamura, R. Suryanarayanan, S. Nimori, M. Apostu, A. Recolevschi, K. Koyama, and N. Kobayashi . Steplike lattice deformation of single crystalline (La0.4Pr0.6)1.2Sr1.8Mn2O7 bilayered Manganite . Phys. Rev. Lett.98 267204 2007年査読

E.A. Tereshina, A.V. Andreev, K. Koyama, Y. Shiokawa, I. Satoh, and K. Watanabe . Magnetic anisotropy and spin reorientation U2Co15Si2 . J. Magn. Magn. Mater316 e515 - e518 2007年査読

A.V. Andreev, E.A. Tereshina, E. Santava, K. Koyama, Y. Homma, I. Satoh, T. Yamamura, Y. Shiokawa, K. Watanabe . Crystal structure and magnetic properties of U2Co17-xSix single crystals . J. Magn. Magn. Mater.310 e598 - e600 2007年査読

A. Himori, M. Tanaka, K. Koyama, K. Watanabe and T. Shigeoka . Magnetic behavior of TbRh2Si2 single crystal . J. Magn. Magn. Mater.310 1770 - 1772 2007年査読

T. Sakon, S. Saito, K. Koyama, S. Awaji, I. Sato, T. Nojima, K. Watanabe and N.K. Sato . Experimental investigation of giant magnetocrystaline anisotropy of UGe2 . Phys. Scr.75 546 - 550 2007年査読

O. Tegus, K. Koyama, J.L. Her, K. Watanabe, E. Bruck, K.H.J. Buschow, F.R. de Boer . X-ray diffraction on MnFeP0.46As0.54 in a magnetic field . Physica B392 151 - 153 2007年査読

K. Wang, T. Fujita, M.W. Chen, T.G. Nieh, H. Okada, K. Koyama, W. Zhang and A. Inoue . Electrical conductivity of a bulk metallic glass composite . Appl. Phys. Lett.91 154101 2007年査読

H. Kato, T. Akiya, M. Sagawa, K. Koyama and T. Miyazaki . Effect of high magnetic field on the coercivity in sintered Nd-Fe-B magnets . J. Magn. Magn. Matter.310 2596 - 2598 2007年査読

K. Koyama, T. Onogi, Y. Mitsui, Y. Nakamoi, S. Orimo, and K. Watanabe . Magnetic phase transition of MnBi under high magnetic fields and high temperature . Mater. Trans.48 2414 - 2418 2007年査読

小野木哲也、小山佳一、渡辺和雄 . 一次相転移物質MnBi の高温・強磁場磁気特性 . 日本金属学会誌71 489 - 493 2007年査読

K. Koyama, T. Iagarashi, H. Okada, K. Watanabe, T. Kanomata, R. Kainuma, W. Ito, K. Oikawa, K. Ishida . Magnetic and thermoelectric properties of Ni50Mn36Sn14 in high magnetic fields . J. Magn. Magn. Mater.310 e994 - e995 2007年査読

M. Kimata, Y. Oshima, H. Ohta, K. Koyama, M. Motokawa, H.M. Yamamoto, and R. Kato . Low-temperature Fermi surface of the organic conductor β”-(BEDT-TTF)(TCNQ)(1-x)(F1-TCNQ)x (x=0, 0.05) from magnetooptical measurements . Phys. Rev. B75 45126 2007年査読

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