Inelastic X-Ray Scattering Study of the Metal-Antiferromagnetic Insulator Transition inV2O3

We use inelastic x-ray scattering to study changes in the electronic excitation spectrum due to the metal-to-antiferromagnetic insulator transition in ${\mathrm{V}}_2$ ${\mathrm{O}}_3$. The spectra reveal three principal features—a plasmonlike excitation at an energy loss of 12 eV which disperses with momentum transfer, a nondispersive peak at 9.2 eV, and a shoulder near 2 eV that appears only in the antiferromagnetic insulator phase. The 9.2 eV peak can be associated with a new type of valence band exciton, while the low energy shoulder is consistent with the opening up of a Hubbard gap.