X-ray spectroscopic study of the electronic structure ofCuCrO2

The electronic structure of the $p$-type transparent conducting oxide ${\text{CuCrO}}_{2}$ 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 $\text{Cu}\text{ }3d$ and $\text{Cr}\text{ }3d$ states while the lower valence-band states are of dominant $\text{O}\text{ }2p$ atomic character, but with pronounced mutual hybridization among $\text{Cu}\text{ }3d$, $\text{Cr}\text{ }3d$, and $\text{O}\text{ }2p$ states. Site specific electronic excitations have been studied by resonant inelastic x-ray scattering at the $\text{Cu}\text{ }L$ and $\text{Cr}\text{ }L$ edges. Inelastic loss at the $\text{Cu}\text{ }L$ edge is dominated by on-site interband excitations similar to those found in ${\text{Cu}}_{2}\text{O}$, while at the $\text{Cr}\text{ }L$ edge localized excitations arising from ligand field splitting of the $\text{Cr}\text{ }3d$ levels are observed. Mg doping on the Cr sites in ${\text{CuCrO}}_{2}$ 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 ${\text{CuCrO}}_{2}$ carried out using density-functional methods corrected for onsite Coulomb repulsion.