Influence of many-body correlation and mixed-valence fluctuations on X-ray magnetic circular dichroism and resonant inelastic X-ray scattering spectra

X-ray magnetic circular dichroism (XMCD) and resonant inelastic X-ray scattering with magnetic circular dichroism (RIXS-MCD) provide unparalleled insights into the electronic and magnetic dynamics of complex materials. However, interpreting their spectra in mixed-valence systems remains challenging due to intricate many-body interactions and enhanced charge fluctuations. In this study, by utilizing the Anderson impurity model with a full consideration of charge transfer (CT), many-body core-valence exchange correlation (CVEC) effects, and Jahn-Teller (JT) distortions, we systematically investigate the XMCD and RIXS-MCD spectra for a prototypical mixed-valence ferromagnet, La0.7Sr0.3MnO3 film. We demonstrate that simple calculation with limited CT effects fails to capture characteristic substructures observed experimentally. In contrast, an adequate treatment of CT and CVEC effects yields a more consistent description of both XMCD and RIXS-MCD spectra, providing practical guidance for the interpretation of dichroic x-ray spectroscopies in mixed-valence transition-metal oxides. Furthermore, we discuss the role of the JT effect in Mn3+ ions in the determination of their spectra. Although X-ray magnetic circular dichroism (XMCD) and resonant inelastic X-ray scattering with magnetic circular dichroism (RIXS-MCD) provide insights into the electronic and magnetic dynamics of complex materials, interpreting spectra from mixed-valence systems is challenging due to the presence of many-body interactions and enhanced charge fluctuations. Here, the authors use an Anderson impurity model that takes into account charge transfer (CT), many-body core-valence exchange correlation (CVEC) effects and Jahn-Teller (JT) distortions, discussing the role of the JT effect in Mn3+ ions in the determination of their spectra and showing that an adequate treatment of charge transfer and many-body core-valence exchange correlation effects yields a more consistent description of both XMCD and RIXS-MCD data.