Charge transfer at the metal-insulator transition inV2O3thin films by resonant inelastic x-ray scattering

Abstract

The metal-insulator transition in ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ thin films has been studied by resonant inelastic x-ray scattering (RIXS) at the V ${L}_{3}$ edge. Features belonging to $d\text{\ensuremath{-}}d$ excitations, charge transfer between $\mathrm{O}\phantom{\rule{0.2em}{0ex}}2p$ and $\mathrm{V}\phantom{\rule{0.2em}{0ex}}3d$ states, and normal x-ray emissionlike decay indicate that intraband, interband, and intersite transitions are involved. In particular, our findings are compatible with a more pronounced density of unoccupied nondegenerate ${a}_{1g}$ states in the paramagnetic insulator (PI) phase compared to the paramagnetic metal (PM) or antiferromagnetic insulator (AFI) phases. The $\mathrm{O}\phantom{\rule{0.2em}{0ex}}2p$ to $\mathrm{V}\phantom{\rule{0.2em}{0ex}}3d$ charge transfer is reduced in the PI phase compared to both the PM and AFI phases. The RIXS spectra also provide an estimate of the crystal-field splitting for ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$.