Analyzing the Local Electronic Structure of Co₃O₄ Using 2p3d Resonant Inelastic X-ray Scattering

We present the cobalt 2p3d resonant inelastic X-ray scattering (RIXS) spectra of Co₃O₄. Guided by multiplet simulation, the excited states at 0.5 and 1.3 eV can be identified as the ⁴ T ₂ excited state of the tetrahedral Co²⁺ and the ³ T ₂ excited state of the octahedral Co³⁺, respectively. The ground states of Co²⁺ and Co³⁺ sites are determined to be high-spin ⁴ A ₂(T ) and low-spin ¹ A ₁ (O ), respectively. It indicates that the high-spin Co²⁺ is the magnetically active site in Co₃O₄. Additionally, the ligand-to-metal charge transfer analysis shows strong orbital hybridization between the cobalt and oxygen ions at the Co³⁺ site, while the hybridization is weak at the Co²⁺ site.