X-ray spectroscopic study of the electronic structure of CuCrO2

The electronic structure of the p-type transparent conducting oxide CuCrO2 has been studied by x-ray photoemission, x-ray absorption, and x-ray emission spectroscopies. The upper part of the valence band derives mainly from Cu 3d and Cr 3d states while the lower valence-band states are of dominant O 2p atomic character, but with pronounced mutual hybridization among Cu 3d, Cr 3d, and O 2p states. Site specific electronic excitations have been studied by resonant inelastic x-ray scattering at the Cu L and Cr L edges. Inelastic loss at the Cu L edge is dominated by on-site interband excitations similar to those found in Cu2O, while at the Cr L edge localized excitations arising from ligand field splitting of the Cr 3d levels are observed. Mg doping on the Cr sites in CuCrO2 is shown to lead to a pronounced shift in the Fermi level toward the edge of the valence band. The experimental data are compared to electronic structure calculations on CuCrO2 carried out using density-functional methods corrected for onsite Coulomb repulsion.