Analysis of Incident-Photon-Energy and Polarization Dependent Resonant Inelastic X-Ray Scattering from La$_{2}$CuO$_{4}$

TL;DR

This paper analyzes how incident-photon energy and polarization affect RIXS spectra at the Cu K-edge in La2CuO4, combining ab initio calculations and theoretical models to explain spectral variations.

Contribution

It provides a detailed theoretical framework for understanding incident-photon and polarization dependence in RIXS spectra, integrating ab initio and multiorbital models.

Findings

Spectra show rich structures in 2-5 eV energy-loss range.

Spectral features vary with momentum and incident-photon energy.

The changes are explained by combined effects of photon-dependent factors and density-density correlations.

Abstract

We present a detailed analysis of the incident-photon-energy and polarization dependences of the resonant inelastic x-ray scattering (RIXS) spectra at the Cu $K$ edge in La$_{2}$CuO$_{4}$. Our analysis is based on the formula developed by Nomura and Igarashi, which describes the spectra by a product of an incident-photon-dependent factor and a density-density correlation function for 3d states. We calculate the former factor using the $4p$ density of states from an ab initio band structure calculation and the latter using a multiorbital tight-binding model within the Hartree-Fock approximation and the random phase approximation. We obtain spectra with rich structures in the energy-loss range 2-5 eV, which vary with varying momentum and incident-photon energy, in semi-quantitative agreement with recent experiments. We clarify the origin of such changes as a combined effect of the incident-photon-dependent factor and the density-density correlation function.