Speaker
Description
The physics of heavy 5d transition metal oxides can be remarkably different from that of their lighter 3d counterparts. In particular, the presence of strong spin-orbit coupling (SOC) effects can lead to the formation of exotic ground states such as spin-orbital Mott insulators, topological insulators, Weyl semimetals, and quantum spin liquids. In materials with an edge-sharing octahedral crystal structure, large SOC can also give rise to highly anisotropic, bond-dependent, Kitaev interactions. The first, and thus far the best, experimental realizations of Kitaev magnetism are honeycomb lattice materials: the 5d iridates A$_2$IrO$_3$ and the 4d halide $\alpha$-RuCl$_3$. However, there has recently been a growing interest in the search for Kitaev magnetism in other families of materials, such as the double perovskite iridates (A$_2$BIrO$_6$) and iridium halides (A$_2$IrX$_6$). In this talk I will describe what we can learn about these novel materials using synchrotron x-ray scattering and spectroscopy techniques, including Resonant Inelastic X-ray Scattering (RIXS) and X-ray Absorption Spectroscopy (XAS). By revealing detailed information about the crystal electric field splitting, SOC strength, and magnetic excitation spectrum, these techniques provide an ideal probe of spin-orbit-driven ground states and Kitaev magnetism.
