Analysis of Resonant Inelastic X-Ray Scattering in Stripe-Ordered Nickelate

TL;DR

This paper provides a theoretical analysis of RIXS spectra in stripe-ordered La_{2-x}Sr_xNiO_4 at x=1/3, explaining the low-energy tail observed at the stripe vector Q and discussing its microscopic origin.

Contribution

It introduces a realistic tight-binding and Hartree-Fock model combined with RPA to analyze RIXS spectra in stripe-ordered nickelates, explaining experimental anomalies.

Findings

RIXS spectra show a low-energy tail at the stripe vector Q.

The anomalous momentum dependence is explained microscopically.

Theoretical results agree with recent experimental observations.

Abstract

We analyze theoretically the resonant inelastic x-ray scattering (RIXS) at the Ni K edge in the stripe-ordered state of La_{2-x}Sr_xNiO_4 at x=1/3. In the calculation of RIXS spectra, the stripe-ordered ground state is described within the Hartree-Fock approximation by using a realistic tight-binding model for Ni3d\gamma and O2p_{x, y} orbitals, and the electron correlations in the electronic excitation processes are taken into account within the random-phase approximation. The calculated RIXS spectrum shows a tail toward the low-energy region when the momentum transfer of photons equals the stripe vector Q, being consistent with a recent experimental result. The origin of this anomalous momentum dependence of RIXS spectra is discussed microscopically.