Lattice coupling and Franck-Condon effects in K-edge resonant inelastic X-ray scattering

TL;DR

This paper explores how lattice vibrations influence Cu K-edge RIXS spectra in CuB2O4, revealing that including lattice effects explains anomalies not accounted for by electron-only models, with broader implications for transition metal oxides.

Contribution

It introduces a model incorporating lattice degrees of freedom to explain RIXS anomalies in CuB2O4, advancing understanding of electron-lattice interactions in transition metal oxides.

Findings

Lattice effects qualitatively explain RIXS anomalies.

Electron-only models are insufficient for certain RIXS features.

Implications extend to higher-dimensional transition metal oxides.

Abstract

We discuss recent Cu K-edge resonant inelastic scattering (RIXS) results for CuB2O4, a model system consisting of electronically-isolated CuO4 plaquettes, which exhibits anomalies in the incident photon energy dependence that are not captured by electron-only models. We show that these anomalous features can be qualitatively described by extending the electron-only considerations to include the lattice degrees of freedom. Our findings have important general implications for the interpretation of K-edge RIXS results for electronically higher-dimensional transition metal oxides.