Theory of spin-excitation anisotropy in the nematic phase of FeSe obtained from RIXS measurements

TL;DR

This paper models the high-energy spin-excitation anisotropy in FeSe's nematic phase using an itinerant approach with RPA, successfully matching recent RIXS experimental data.

Contribution

It introduces a theoretical model that explains RIXS measurements of spin-excitation anisotropy in FeSe's nematic phase, linking it to magnetic fluctuations.

Findings

The model reproduces the high-energy spin-excitation anisotropy observed in RIXS.

It demonstrates the applicability of an itinerant RPA-based approach to FeSe.

The calculated RIXS cross section aligns with experimental data.

Abstract

Recent resonant inelastic x-ray scattering (RIXS) experiments have detected a significant high-energy spin-excitation anisotropy in the nematic phase of the enigmatic iron-based superconductor FeSe, whose origin remains controversial. We apply an itinerant model previously used to describe the spin-excitation anisotropy as measured by neutron scattering measurements, with magnetic fluctuations included within the RPA approximation. The calculated RIXS cross section exhibits overall agreement with the RIXS data, including the high energy spin-excitation anisotropy.