X-ray absorption and magnetic circular dichroism studies of spin-orbital magnetism in the three-dimensional Kitaev honeycomb γ-Li₂IrO₃

Transition metal oxides are an exiting platform for exploring novel states of quantum matter. The choice of transition metal and its crystalline structure determine the magnitude of spin orbit coupling and electronic correlations, parameters that can be carefully tuned to create Mott insulators, topological insulators, superconductors and spin liquids. The 5d transition metal oxide lithium iridate γ-Li₂IrO₃, a Mott insulator and Kitaev spin liquid candidate, displays particularly strong spin orbit coupling, several honeycomb crystal structures, and magnetic ground states that can be tuned with applied pressure and magnetic fields; however, there are still open questions about its electronic structure. X-ray absorption spectroscopy was used to probe the γ-Li₂IrO₃ valence states and measure spin orbit coupling and crystal field splitting energy scales. In addition, X-ray Magnetic Circular Dichroism measurements were used to extract the spin and orbital content of the iridium magnetic moment. Evidence from these experiments will help to build a more accurate picture of the electronic states driving magnetism in this material.