Continuum Charge Excitations in High-Valence Transition-Metal Oxides Revealed by Resonant Inelastic X-ray Scattering

TL;DR

This paper uses advanced theoretical methods to analyze how electronic and crystal structures influence charge excitations observed in RIXS spectra of high-valence transition-metal oxides, revealing the origin of specific spectral features.

Contribution

It provides a detailed theoretical explanation of Raman-like and fluorescencelike features in RIXS spectra, linking them to material-specific electronic and structural properties.

Findings

FL feature connected to electronic structure details

Material-dependent excitation of electron-hole continuum

Theoretical spectra match experimental observations

Abstract

We present a theoretical investigation of the origin of Raman-like and fluorescencelike (FL) features of resonant inelastic x-ray scattering (RIXS) spectra. Using a combination of local-density approximation + dynamical mean-field theory and a configuration interaction solver for Anderson impurity model, we calculate the $L$-edge RIXS and x-ray absorption spectra of high-valence transition-metal oxides LaCuO$_3$ and NaCuO$_2$. We analyze in detail the behavior of the FL feature and show how it is connected to the details of electronic and crystal structure. On the studied compounds we demonstrate how material details determine whether the electron-hole continuum can be excited in the $L$-edge RIXS process.