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Al
O
Nakajima, Taro*; Mitsuda, Setsuo*; Inami, Toshiya; Terada, Noriki*; Osumi, Hiroyuki*; Prokes, K.*; Podlesnyak, A.*
Physical Review B, 78(2), p.024106_1 - 024106_10, 2008/07
Times Cited Count：37 Percentile：77.36(Materials Science, Multidisciplinary)
O
; Understanding of the details of the Ising spin and the competitive interactions which made the devil's flower bloomOwada, Kenji; Fujii, Yasuhiko; Muraoka, Jiro*; Nakao, Hironori*; Murakami, Yoichi*; Noda, Yukio*; Osumi, Hiroyuki*; Ikeda, Naoshi*; Shobu, Takahisa; Isobe, Masahiko*; et al.
Hoshako, 21(2), p.87 - 96, 2008/03
Devil's flower has been found in a temperature-pressure phase diagram of NaVO, which shows a charge disproportionation (CD) at ambient pressure. By a complementary use of an X-ray structural analysis and a resonant X-ray diffraction, which is sensitive to CD, we have investigated the structural relationship between two ground states appeared in lower and higher pressure regions including the charge arrangements. It has been clarified that two equivalent types of charge arrangement in CD correspond to the Ising variable in NaVO. The atomic shifts are regarded as linearly coupled to the Ising spins. The results lead us to the conclusion that it is the first time that the devil's flower blooms in a charge-disproportionation system. The results also lead us to a hypothesis that the competitive interactions between a Ising spins may result from the Ising spin-phonon coupling.
O under high pressure; A Synchrotron X-ray diffraction studyOwada, Kenji; Fujii, Yasuhiko; Muraoka, Jiro*; Nakao, Hironori*; Murakami, Yoichi; Noda, Yukio*; Osumi, Hiroyuki*; Ikeda, Naoshi*; Shobu, Takahisa; Isobe, Masahiko*; et al.
Physical Review B, 76(9), p.094113_1 - 094113_10, 2007/09
Times Cited Count：10 Percentile：43.26(Materials Science, Multidisciplinary)Structural relations between two ground states of the ANNNI (Axial Next Nearest Neighbor Ising) compound NaVO, C
- and C
-phases below and above the transition pressure 
= 1 GPa, were investigated by X-ray diffraction and scattering techniques. The structure of the C-phase is well explained by the 
(
) pattern which is one of four layers (
) of the C-phase, however, the amount of the atomic shifts under the conditions 1.6 GPa and 6 K is 27% that under ambient pressure. On the other hand, resonant X-ray scattering showed that the charges are disproportionated under high pressure. Based on these facts, it was concluded that charge disproportionation corresponds to the Ising variable in NaVO, where the atomic shifts are regarded as linearly coupled to the Ising spins. These results lead to the hypothesis that the competitive interactions between the Ising spins may result from the Ising spin-phonon coupling.
O
Ikeda, Naoshi*; Osumi, Hiroyuki*; Owada, Kenji; Ishii, Kenji; Inami, Toshiya; Kakurai, Kazuhisa; Murakami, Yoichi*; Yoshii, Kenji; Mori, Shigeo*; Horibe, Yoichi*; et al.
Nature, 436(7054), p.1136 - 1138, 2005/08
Times Cited Count：856 Percentile：99.75(Multidisciplinary Sciences)By means of resonant X-ray scattering experiments using synchrotron radiation of SPring-8, it was found that a mixed-valence system LuFeO is a ferroelectric material owing to a real-space charge-ordering of Fe
and Fe
. This ordering is rooted in a charge frustration between the Fe ions on a triangular lattice. The new mechanism of ferroelectricity shown in the present paper offers great potential for designing future ferroelectric devices to be coupled or controlled with the degrees of freedom of electron: charge, spin and orbital.
HNH
)CuCl studied by resonant and non-resonant X-ray scatterings under high pressureOwada, Kenji; Ishii, Kenji; Inami, Toshiya; Murakami, Yoichi; Shobu, Takahisa*; Osumi, Hiroyuki*; Ikeda, Naoshi*; Oishi, Yasuo*
Physical Review B, 72(1), p.014123_1 - 014123_10, 2005/07
Times Cited Count：28 Percentile：69.89(Materials Science, Multidisciplinary)The effects of hydrostatic pressure on a structure and the corresponding resonant X-ray scattering (RXS) spectrum have been investigated for the hole-orbital-ordered compound (CHNH)CuCl. We have found a structural phase transition at Pc=4 GPa. The reduction of the Jahn-Teller distortion (JTD) toward Pc is also ascertained by structural analyses. The gradual change in the color of the crystal is also observed in connection with the structural change near Pc. We experimentally confirmed that the RXS intensity comes from the polarization of the density of states of px and py symmetries, which is mainly dominated not by the on-site 3d-4p Coulomb interaction but by the JTD of the CuCl
octahedron. The RXS study under a high pressure shows no striking change as JTD is suppressed by the application of pressure. On the other hand, the RXS intensity becomes zero above Pc. The results indicate that the local environment of the Cu ion markedly changes. Two possible structures above Pc are proposed.
Si using neutron and synchrotron radiation experimentsHonda, Fuminori; Metoki, Naoto; Osumi, Hiroyuki*; Tsutsui, Satoshi*; Ishii, Kenji; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika
no journal, ,
no abstracts in English
SiHonda, Fuminori; Metoki, Naoto; Osumi, Hiroyuki*; Tsutsui, Satoshi*; Ishii, Kenji; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika*
no journal, ,
no abstracts in English
Si using non-resonant X-ray scatteringOsumi, Hiroyuki*; Honda, Fuminori; Metoki, Naoto; Tsutsui, Satoshi*; Ishii, Kenji; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika*
no journal, ,
no abstracts in English
