Bulk band dispersion in Ti2O3 and V2O3

Abstract

We report here a comprehensive study of the bulk electronic structure of single-crystal ${\mathrm{Ti}}_2$ ${\mathrm{O}}_3$ and ${\mathrm{V}}_2$ ${\mathrm{O}}_3$ using both angle-integrated and angle-resolved photoemission and synchrotron radiation. The electronic structure of these materials is of particular interest because of the metal-insulator transitions which they undergo. Slight (<0.4 eV) dispersion of the cation 3d bands is observed in both materials, supporting a band model for their electronic structure. Large discrepancies are observed between the measured band dispersion and published calculations for both materials. The O 2p emission is too broad to permit extraction of unambiguous band dispersions. Resonant photoemission is observed from cation 3d states in both ${\mathrm{Ti}}_2$ ${\mathrm{O}}_3$ and ${\mathrm{V}}_2$ ${\mathrm{O}}_3$ as the photon energy is swept through the cation 3p→3d optical-absorption edge. A valence-band satellite is resolved in the angle-integrated photoemission spectra from ${\mathrm{V}}_2$ ${\mathrm{O}}_3$; resolving this feature shows that the actual width of the O 2p band in ${\mathrm{V}}_2$ ${\mathrm{O}}_3$ is almost 2.5 eV narrower than previous studies indicated.