Local versus Nonlocal States of La <b> ₂ </b> CoMnO <b> ₆ </b> Observed with 1s2p Resonant Inelastic X-ray Scattering

Co and Mn K-edge multiplets of bimetallic perovskite La2CoMnO6 nanoparticles (NP) and thin films are studied using high-resolution 1s2p resonant inelastic X-ray scattering (1s2p RIXS). Both the La2CoMnO6 NP and thin films exhibit Co2+ and Mn4+ valence states. A strong nonlocal peak is observed in the La2CoMnO6 NP, which becomes weaker in epitaxial La2CoMnO6 thin films grown on a SrTiO3 (0 0 1) substrate. Guided by charge-transfer multiplet calculations, the Co and Mn 1s to 3d quadrupole pre-edge X-ray absorption near-edge structure (XANES) and 1s2p RIXS spectra were calculated, showing good agreement with experimental observations. Using Density Functional Theory (DFT) + U simulations, the metal ions 1s to nonlocal 3d-4p dipole transitions are successfully reproduced. The nonlocal peak can be explained as dipole transitions to metal–metal charge-transfer interactions facilitated by the oxygen 2p state. This study underscores nonlocal hybridizations beyond the local 1s to 3d quadrupole transitions in K-edge X-ray absorption spectra.