Ab initio modeling of resonant inelastic x-ray scattering from Ca2RuO4

TL;DR

This study uses first-principles calculations to model resonant inelastic X-ray scattering spectra of Ca2RuO4, providing insights into its electronic structure and establishing a reliable theoretical approach for similar strongly correlated materials.

Contribution

The paper introduces a comprehensive ab initio method combining DFT with spin-orbit coupling and Coulomb interactions to accurately model RIXS spectra of Ca2RuO4, aligning well with experimental data.

Findings

Good agreement between calculated and experimental RIXS spectra.

Identification of key spectral features related to electronic structure.

Validation of the theoretical approach for complex correlated materials.

Abstract

The single-layered perovskite Ca$_2$RuO$_4$, characterized by a 4$d^4$ electron configuration, has been studied from first principles using density functional theory (DFT) using the generalized gradient approximation, with inclusion of strong on-site Coulomb interactions and spin-orbit coupling (GGA+SO+$U$), in the framework of the fully relativistic, spin-polarized Dirac linear muffin-tin orbital (LMTO) band-structure method. This approach enabled a comprehensive investigation of the electronic structure of Ca$_2$RuO$_4$ through the modeling of relevant spectra obtained from synchrotron-based techniques widely used to probe electronic properties, with a primary focus on resonant inelastic X-ray scattering (RIXS) at the Ru $L_3$ and O $K$ edges. The calculated spectra were thoroughly analyzed with available experimental data reported in the literature. The good agreement between our results and experimental observations for Ca$_2$RuO$_4$ enables a conclusive interpretation of key features in the spectra obtained from the aforementioned techniques. Consequently, this enables us to describe its electronic properties and to establish a solid theoretical approach suitable for routine modeling of spectra, particularly from RIXS, aimed at characterizing the electronic structure and properties of similar or more complex strongly correlated, technologically relevant materials.