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Araki, Shingo*; Hayashida, Minami*; Nishiumi, Naoto*; Manabe, Hiroki*; Ikeda, Yoichi*; Kobayashi, Tatsuo*; Murata, Keizo*; Inada, Yoshihiko*; Wi
niewski, P.*; Aoki, Dai*; et al.
Journal of the Physical Society of Japan, 84(2), p.024705_1 - 024705_8, 2015/02
Times Cited Count：9 Percentile：55.76(Physics, Multidisciplinary)P under high pressureAraki, Shingo*; Hayashida, Minami*; Nishiumi, Naoto*; Manabe, Hiroki*; Ikeda, Yoichi*; Kobayashi, Tatsuo*; Murata, Keizo*; Inada, Yoshihiko*; Winiewski, P.*; Aoki, Dai*; et al.
JPS Conference Proceedings (Internet), 3, p.011081_1 - 011081_6, 2014/06
Yamamoto, Etsuji; Haga, Yoshinori; Ikeda, Shugo; Matsuda, Tatsuma; Akazawa, Teruhiko*; Kotegawa, Hisashi*; Kobayashi, Tatsuo*; Onuki, Yoshichika*
Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.e123 - e125, 2007/03
no abstracts in English
= 1 antiferromagnet observed by specific heat measurementsHagiwara, Masayuki*; Tsujii, Hiroyuki*; Rotundu, C. R.*; Andraka, B.*; Takano, Yasumasa*; Tateiwa, Naoyuki; Kobayashi, Tatsuo*; Suzuki, Takafumi*; Suga, Seiichiro*
Physical Review Letters, 96(14), p.147203_1 - 147203_4, 2006/04
Times Cited Count：19 Percentile：67.21(Physics, Multidisciplinary)Specific-heat experiments on single crystals of the = 1 quasi-one-dimensional bond-alternating antiferromagnet Ni(C
H
N)(NO
)(ClO) (NTENP) have been performed in magnetic fields applied both parallel and perpendicular to the spin chains. We have found for the parallel field configuration that the magnetic specific heat (
) is proportional to temperature (
) above a critical field 
, at which the energy gap vanishes, in a temperature region above that of the long-range ordered state. The ratio = increases as the magnetic field approaches from above. The data are in good quantitative agreement with the prediction of the 
=1 conformal field theory in conjunction with the velocity of the excitations calculated by a numerical diagonalization, providing conclusive evidence for a Tomonaga-Luttinger liquid.
; The de Haas-van Alphen study under pressureSettai, Rikio*; Kubo, Tetsuo*; Shiromoto, Tomoyuki*; Honda, Daisuke*; Shishido, Hiroaki*; Sugiyama, Kiyohiro*; Haga, Yoshinori; Matsuda, Tatsuma; Betsuyaku, Kiyoshi*; Harima, Hisatomo*; et al.
Journal of the Physical Society of Japan, 74(11), p.3016 - 3026, 2005/11
Times Cited Count：62 Percentile：87.38(Physics, Multidisciplinary)We have studied a change of the Fermi surface in an antiferromagnet CeIn via the de Haas-van Alphen experiment under pressure up to 3 GPa. With increasing pressure P, the Neel temperature 
=10 K decreases and becomes zero at a critical pressure Pc 
2.6 GPa. In the pressure region 
, we have observed a large main Fermi surface named a, which indicates that the electronic state of 4 f electron in CeIn changes from localized to itinerant at Pc, as observed in the similar antiferromagnets CeRhSi and CeRhIn
. The cyclotron effective mass 
of this main Fermi surface is extremely enhanced around Pc: 60 
at 2.7 GPa for the magnetic field along the 
100
direction.
under high pressureSakai, Hironori; Kato, Harukazu; Tokunaga, Yo; Kambe, Shinsaku; Walstedt, R. E.; Nakamura, Akio; Tateiwa, Naoyuki*; Kobayashi, Tatsuo*
Journal of Magnetism and Magnetic Materials, 272-276(Suppl.), p.e413 - e414, 2004/05
Times Cited Count：2 Percentile：13.75(Materials Science, Multidisciplinary)The d.c. magnetization of insulating UO under high pressure up to about 1 GPa has been measured using a piston-cylinder cell. Pressure-induced weak ferromagnetism was found to appear at low pressure (about 0.2 GPa). Both the remanent magnetization and the coercive force increase as pressure increases. This weak ferromagnetism may come from spin canting or from uncompensated moments around grain boundaries.
and 
in the ferromagnetic superconductor UGeTateiwa, Naoyuki*; Kobayashi, Tatsuo*; Amaya, Kiichi*; Haga, Yoshinori; Settai, Rikio*; Onuki, Yoshichika
Physical Review B, 69(18), p.180513_1 - 180513_4, 2004/05
Times Cited Count：43 Percentile：83.13(Materials Science, Multidisciplinary)We have investigated the specific heat under high pressure in the ferromagnetic superconductor UGe. Specific heat anomalies at the characteristic temperatures , the superconducting transition temperature, and were directly observed from the high-pressure specific heat measurement. The low-temperature electronic specific heat coefficient increases with increasing pressure, corresponding to the formation of heavy-fermion state near the critical pressure.
Sakai, Hironori; Kato, Harukazu; Tokunaga, Yo; Kambe, Shinsaku; Walstedt, R. E.; Nakamura, Akio; Tateiwa, Naoyuki*; Kobayashi, Tatsuo*
Journal of Physics; Condensed Matter, 15(28), p.S2035 - S2037, 2003/07
Times Cited Count：3 Percentile：21.31(Physics, Condensed Matter)The cubic-fluorite type uranium dioxide UO is an ionically bounded insulator with localized magnetic moments of U
(5
) ions. Under atmospheric pressure, UO exhibits a first order antiferromagnetic transition at 
=30.8 K accompanied by a small lattice distortion. In order to clarify the interrelation between QQ and exchange interactions in this system, we performed d.c. magnetization measurement under high pressure up to about 1 GPa by a piston-cylinder-type cramped cell. From the d.c. magnetization measurements under high pressure (
0.1 GPa), it is found that UO shows a weak-ferromagnetic-like transition at 
30 K, where the transition temperature is almost independent of external pressure up to 1 GPa. The ferromagnetic component per uranium atom is very small (
), although its component is dependent of pressure. This small ferromagnetic component may come from a canted antiferromagnetic ordering.
Si under pressureAraki, Shingo; Nakashima, Miho*; Settai, Rikio*; Kobayashi, Tatsuo*; Onuki, Yoshichika
Acta Physica Polonica B, 34(2, Part1), p.439 - 442, 2003/02
no abstracts in English
Tateiwa, Naoyuki*; Hanazono, Katsumi*; Kobayashi, Tatsuo*; Amaya, Kiichi*; Inoue, Tetsutaro*; Kindo, Koichi*; Koike, Yoshihiro; Metoki, Naoto; Haga, Yoshinori; Settai, Rikio*; et al.
Journal of the Physical Society of Japan, 70(10), p.2876 - 2879, 2001/10
Times Cited Count：61 Percentile：86.54(Physics, Multidisciplinary)no abstracts in English
Metoki, Naoto; Koike, Yoshihiro; Matsuoka, Yuki; Kobayashi, Tatsuo*; Yamashita, Masahiro*
Journal of Magnetism and Magnetic Materials, 226-230(Part.1), p.414 - 416, 2001/05
no abstracts in English
Koike, Yoshihiro; Metoki, Naoto; Morii, Yukio; Kobayashi, Tatsuo*; Ishii, Tomohiko*; Yamashita, Masahiro*
Journal of the Physical Society of Japan, 69(12), p.4034 - 4042, 2000/12
Times Cited Count：6 Percentile：46.5(Physics, Multidisciplinary)no abstracts in English
O
(R: rare earths)Yoshii, Kenji; Matsumura, Daiju; Endo, Naruki; Saito, Hiroyuki; Yoneda, Yasuhiro; Nishihata, Yasuo; Funae, Takeshi*; Ejiri, Hiroki*; Kano, Jun*; Kobayashi, Tatsuo*; et al.
no journal, ,
We have investigated the substitution effects at the rare-earth (R) site in multiferroic RFeO (R: Y, Ho-Lu) to explore a new phase of this system. From EXAFS measurements for the R atoms, the large R
ions (such as Dy) was partially substituted in RFeO. Powder X-ray diffraction showed that this material had a single-phase RFeO-type structure (space group R-3m). The simulated EXAFS spectrum reproduced the characteristics of the experimental spectrum, confirming that R is actually settled at the rare earth site. The other results, such as the magnetic properties, will be reported at the conference.
