Electronic Structure of Low-Dimensional 4d5 Oxides: Interplay of Ligand Distortions, Overall Lattice Anisotropy, and Spin鈥揙rbit Interactions

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• 作者：Vamshi M. Katukuri ; Karla Roszeitis ; Viktor Yushankhai ; Alexander Mitrushchenkov ; Hermann Stoll ; Michel van Veenendaal ; Peter Fulde ; Jeroen van den Brink ; Liviu Hozoi
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：May 19, 2014
• 年：2014
• 卷：53
• 期：10
• 页码：4833-4839
• 全文大小：330K
• 年卷期：v.53,no.10(May 19, 2014)
• ISSN：1520-510X

文摘

The electronic structure of the low-dimensional 4d⁵ 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_2g⁵鈥搕_2g⁴e_g¹ couplings via spin鈥搊rbit interactions produce in Sr₂RhO₄ ground-state expectation values significantly larger than 1, quite similar to theoretical and experimental data for 5d⁵ spin鈥搊rbit-driven oxides such as Sr₂IrO₄. On the other hand, in Ca₃CoRhO₆, the values are lower because of larger t_2g鈥揺_g splittings. Future X-ray magnetic circular dichroism experiments on these 4d oxides will constitute a direct test for the values that we predict here, the importance of many-body t_2g鈥揺_g couplings mediated by spin鈥搊rbit interactions, and the role of low-symmetry fields associated with the extended surroundings.