Electronic Structure of Low-Dimensional 4d5 Oxides: Interplay of Ligand Distortions, Overall Lattice Anisotropy, and Spin-Orbit Interactions
Electronic Structure of Low-Dimensional 4d5 Oxides: Interplay of Ligand Distortions, Overall Lattice Anisotropy, and Spin-Orbit Interactions
复制标题
DOI：
10.1021/ic402653f
复制
发表时间：
2014-05-19
影响因子：
4.6
通讯作者：
Hozoi, Liviu
中科院分区：
文献类型：
--
作者：
Katukuri, Vamshi M.;Roszeitis, Karla;Hozoi, Liviu
采用嵌入团簇量子化学方法研究了低维4d（5）氧化物Sr 2 RhO 4和Ca 3CoRhO 6的电子结构.一个负的四边形样的t（2g）分裂计算Sr 2 RhO 4和一个负的三角形样的分裂预测为Ca 3CoRhO 6，尽管有正的四面体畸变在前者的材料和立方氧八面体在后者。我们的研究结果带来了前景的作用，较长范围的晶体各向异性在产生非立方势，竞争与本地扭曲的配体笼，一个问题没有解决在标准教科书上的晶体场理论。我们还表明，相当大的t（2g）（5）-t（2g）（4）e（g）（1）耦合通过自旋-轨道相互作用产生的Sr 2 RhO 4（Z）=基态期望值显着大于1，非常类似的理论和实验数据为5d（5）自旋-轨道驱动的氧化物，如Sr 2 IrO 4。另一方面，在Ca_3CoRhO_6中，由于较大的t（2g）-e（g）分裂，（Z）值较低。未来对这些4d氧化物的X射线磁性圆二色性实验将构成对我们在这里预测的（Z）值的直接测试，由自旋轨道相互作用介导的多体t（2g）-e（g）耦合的重要性，以及与扩展环境相关的低对称性场的作用。
The electronic structure of the low-dimensional 4d(5) oxides Sr2RhO4 and Ca3CoRhO6 is herein investigated by embedded-cluster quantum chemistry calculations. A negative tetragonal-like t(2g) splitting is computed in Sr2RhO4 and a negative trigonal-like splitting is predicted for Ca3CoRhO6, in spite of having positive tetragonal distortions in the former material and cubic oxygen octahedra in the latter. Our findings bring to the foreground the role of longer-range crystalline anisotropy in generating noncubic potentials that compete with local distortions of the ligand cage, an issue not addressed in standard textbooks on crystal-field theory. We also show that sizable t(2g)(5)-t(2g)(4)e(g)(1) couplings via spin-orbit interactions produce in Sr2RhO4 (Z) = ground-state expectation values significantly larger than 1, quite similar to theoretical and experimental data for 5d(5) spin-orbit-driven oxides such as Sr2IrO4. On the other hand, in Ca3CoRhO6, the (Z) values are lower because of larger t(2g)-e(g) splittings. Future X-ray magnetic circular dichroism experiments on these 4d oxides will constitute a direct test for the (Z) values that we predict here, the importance of many-body t(2g)-e(g) couplings mediated by spin-orbit interactions, and the role of low-symmetry fields associated with the extended surroundings.