Excitonic dispersion of the intermediate spin state in LaCoO3 revealed by resonant inelastic x-ray scattering

Abstract

We report Co L3-edge resonant inelastic x-ray scattering on LaCoO3 at 20 K. We observe excitations with sizable dispersion that we identify as intermediate-spin (IS) states. Theoretical calculations that treat the IS states as mobile excitons propagating on the low-spin background support the interpretation. The present result shows that mobility substantially reduces the energy of IS excitations in part of the Brillouin zone, which makes them important players in the low-energy physics of LaCoO3 together with immobile high-spin excitations.