Analyzing the Local Electronic Structure of CoO Using 2p3d Resonant Inelastic X-ray Scattering.

We present the cobalt 2p3d resonant inelastic X-ray scattering (RIXS) spectra of CoO. Guided by multiplet simulation, the excited states at 0.5 and 1.3 eV can be identified as the excited state of the tetrahedral Co and the excited state of the octahedral Co, respectively. The ground states of Co and Co sites are determined to be high-spin ( ) and low-spin ( ), respectively. It indicates that the high-spin Co is the magnetically active site in CoO. Additionally, the ligand-to-metal charge transfer analysis shows strong orbital hybridization between the cobalt and oxygen ions at the Co site, while the hybridization is weak at the Co site.