Theory of Successive Transitions in Vanadium Spinels and Order of Orbitals and Spins
Theory of Successive Transitions in Vanadium Spinels and Order of Orbitals and Spins
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DOI：
10.1143/ptps.160.203
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发表时间：
2005-06
影响因子：
--
通讯作者：
Y. Motome;H. Tsunetsugu
中科院分区：
文献类型：
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作者：
Y. Motome;H. Tsunetsugu
我们从理论上研究了钒尖晶石氧化物中具有（2g） 2电子构型的连续跃迁。这些化合物在~ 50 K时发生结构转变，在~ 40 K时发生反铁磁转变。由于钒离子的三倍t - 2g轨道被部分占据，并且钒构成了一个几何受挫的焦绿石晶格，该系统提供了一个特殊的例子来研究受挫晶格上自旋、轨道和晶格自由度之间的相互作用。我们研究了具有Jahn-Teller耦合和/或自旋-轨道超交换相互作用的模型，并得出结论，这两种作用之间的激烈竞争解释了钒尖晶石的热力学。讨论了量子涨落和相对论自旋-轨道耦合的影响。
We have theoretically studied successive transitions in vanadium spinel oxides with (t 2g ) 2 electron configuration. These compounds show a structural transition at ∼ 50 K and an antiferromagnetic transition at ∼ 40 K. Since threefold t 2g orbitals of vanadium cations are occupied partially and vanadiums constitute a geometrically-frustrated pyrochlore lattice, the system provides a particular example to investigate the interplay among spin, orbital and lattice degrees of freedom on frustrated lattice. We examine the models with the Jahn-Teller coupling and/or the spin-orbital superexchange interaction, and conclude that keen competition between these two contributions explains the thermodynamics of vanadium spinels. Effects of quantum fluctuations as well as relativistic spin-orbit coupling are also discussed.