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Covalency-driven collapse of strong spin-orbit coupling in face-sharing iridium octahedra

Authors :
Ye, Mai
Kim, Heung-Sik
Kim, Jae-Wook
Won, Choong-Jae
Haule, Kristjan
Vanderbilt, David
Cheong, Sang-Wook
Blumberg, Girsh
Source :
Phys. Rev. B 98, 201105 (2018)
Publication Year :
2018

Abstract

We report $\textit{ab-initio}$ density functional theory calculation and Raman scattering results to explore the electronic structure of Ba$_5$CuIr$_3$O$_{12}$ single crystals. This insulating iridate, consisting of face-sharing IrO$_6$ octahedra forming quasi-one-dimensional chains, cannot be described by the local $j_{\rm eff}$=1/2 moment picture commonly adopted for discussing electronic and magnetic properties of iridate compounds with IrO$_6$ octahedra. The shorter Ir-Ir distance in the face-sharing geometry, compared to corner- or edge-sharing structures, leads to strong covalency between neighboring Ir. Then this strong covalency results in the formation of molecular orbitals (MO) at each Ir trimers as the low-energy electronic degree of freedom. The theoretically predicted three-peak structure in the joint density of states, a distinct indication of deviation from the $j_{\rm eff}$=1/2 picture, is verified by observing the three-peak structure in the electronic excitation spectrum by Raman scattering.<br />Comment: 5 pages, 5 figures, with a Supplementary Information

Details

Database :
arXiv
Journal :
Phys. Rev. B 98, 201105 (2018)
Publication Type :
Report
Accession number :
edsarx.1808.10407
Document Type :
Working Paper
Full Text :
https://doi.org/10.1103/PhysRevB.98.201105