Stability of the local electronic properties of La3Ni2O7 under pressure

Motivated by the recent discovery of superconductivity in bulk La3Ni2O7 under pressure, we investigated its local electronic structure—specifically the Ni oxidation state, 3d occupancy, spin configuration, and 3d − 2p hybridization—using Ni K-edge x-ray absorption spectroscopy (XAS) and Kβ x-ray emission spectroscopy (XES), complemented by density functional theory (DFT) and spectral simulations. Despite the average valence of ∼2.5+ indicated by XAS, analysis of the XES spectra revealed 3d8L electronic configuration with low-spin ground state. Under HP up to 30 GPa and low T down to 10 K, we find no evidence of changes in Ni valence, 3d occupancy, or spin state, effectively ruling out pressure-induced spin-state transitions proposed in some theoretical models. Additional La L3-edge XAS measurements show only subtle spectral modifications, inconsistent with significant 3d−5d charge transfer. These results suggest that the pressure-induced superconductivity in La3Ni2O7 is unlikely linked with substantial changes in the local electronic structure.