Magnetic transition and orbital degrees of freedom in vanadium spinels

被引:139
作者
Tsunetsugu, H [1 ]
Motome, Y
机构
[1] Kyoto Univ, Yukawa Inst Theoret Phys, Kyoto 6068502, Japan
[2] Natl Inst Adv Ind Sci & Technol, Japan Sci & Technol Corp, ERATO, Tokura Spin Superstruct Project, Tsukuba, Ibaraki, Japan
来源
PHYSICAL REVIEW B | 2003年 / 68卷 / 06期
关键词
D O I
10.1103/PhysRevB.68.060405
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
We propose a scenario for the two phase transitions in AV(2)O(4) (A=Zn, Mg, Cd), based on an effective spin-orbital model on the pyrochlore lattice. At high temperatures, spin correlations are strongly frustrated due to the lattice structure, and the transition observed at similar to50 K is attributed to an orbital order, supported by Jahn-Teller lattice distortion. This orbital order introduces spatial modulation of spin-exchange couplings depending on the bond direction. This partially releases the frustration and leads to a spin order observed at similar to40 K. We also study the stable spin configuration by taking account of third-neighbor exchange couplings and quantum fluctuations. The result is consistent with the experimental results.
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页数:4
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