Probing the low-energy orbital texture of Mott insulating Ca2RuO4

Spin-orbit coupled systems display a rich variation of intricate quantum matter phases. The Mott insulating states of Sr2IrO4 and Ca2RuO4 are thought to be triggered by a combination of electron correlations and spin-orbit coupling. In Ca2RuO4, where spin-orbit coupling has a comparable energy scale to the crystal field splitting's, neutron scattering has successfully probed dispersive single magnon excitations. However, neutron scattering does not provide insight into the orbital character of these excitations. It is widely believed that interactions responsible for the Mott insulating state are encoded into this orbital texture. With the improvements provided by the ERIXS spectrometer, it is now possible to probe both orbital and spin excitations simultaneously in Ca2RuO4. We therefore propose to study the low-energy spin-orbital excitation spectrum of Ca2RuO4 via the oxygen K-edge at which ID32 delivers an energy resolution just below 30 meV.