Critical competition between two distinct orbital-spin ordered states in perovskite vanadates

ペロブスカイトバナジウム酸化物における2つの軌道・スピン秩序状態間の臨界競合

藤岡 淳*; 安江 俊夫*; 宮坂 茂樹*; 山崎 裕一*; 有馬 孝尚*; 佐賀山 基*; 稲見 俊哉; 石井 賢司; 十倉 好紀*

Fujioka, Jun*; Yasue, Toshio*; Miyasaka, Shigeki*; Yamazaki, Yuichi*; Arima, Takahisa*; Sagayama, Hajime*; Inami, Toshiya; Ishii, Kenji; Tokura, Yoshinori*

We have investigated the spin/orbital phase diagram in the perovskite orthovanadate VO ( = Eu, Y, Dy, and Ho) by measurements of magnetization, dielectric constant, specific heat, Raman scattering spectra, and X-ray diffraction, focusing on the interplay between the V spin and the moment of the ion. The results cannot be uniquely explained in terms of the exchange interaction between the V spin and the -ion moment. By comparing this phase diagram with the spin/orbital ordering in TbVO, it is evident that the critical competition between the C-type spin/G-type orbital ordered phase and the G-type spin/C-type orbital ordered one depends not only on the GdFeO-type lattice distortion but also on the presence of the moment of the ion. The magnetic field induced phase transition of the spin/orbital ordering is achieved concomitantly with polarizing moments for DyVO and HoVO. The results cannot be uniquely explained in terms of the exchange interaction between the V spin and the -ion moment. The coupling of the moment polarization with the lattice distortion tied with the orbital ordering of the V sublattice may also be relevant to this field induced phase transition.