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Spin-orbit excitations and electronic structure of the putative Kitaev magnetα−RuCl3

Authors :
Yao Tian
L. J. Sandilands
Kenneth S. Burch
Heung-Sik Kim
Hae-Young Kee
Anjan Reijnders
K. W. Plumb
Young-June Kim
Source :
Physical Review B. 93
Publication Year :
2016
Publisher :
American Physical Society (APS), 2016.

Abstract

Mott insulators with strong spin-orbit coupling have been proposed to host unconventional magnetic states, including the Kitaev quantum spin liquid. The $4d$ system $\ensuremath{\alpha}\ensuremath{-}{\mathrm{RuCl}}_{3}$ has recently come into view as a candidate Kitaev system, with evidence for unusual spin excitations in magnetic scattering experiments. We apply a combination of optical spectroscopy and Raman scattering to study the electronic structure of this material. Our measurements reveal a series of orbital excitations involving localized total angular momentum states of the Ru ion, implying that strong spin-orbit coupling and electron-electron interactions coexist in this material. Analysis of these features allows us to estimate the spin-orbit coupling strength, as well as other parameters describing the local electronic structure, revealing a well-defined hierarchy of energy scales within the Ru $d$ states. By comparing our experimental results with density functional theory calculations, we also clarify the overall features of the optical response. Our results demonstrate that $\ensuremath{\alpha}\ensuremath{-}{\mathrm{RuCl}}_{3}$ is an ideal material system to study spin-orbit coupled magnetism on the honeycomb lattice.

Details

ISSN :
24699969 and 24699950
Volume :
93
Database :
OpenAIRE
Journal :
Physical Review B
Accession number :
edsair.doi...........70288d06eda7749f3413d40627872a9a
Full Text :
https://doi.org/10.1103/physrevb.93.075144