Itinerant approach to magnetic neutron scattering of FeSe: effect of orbital selectivity

TL;DR

This paper investigates the magnetic excitation spectrum of FeSe considering orbital selectivity, showing good agreement with neutron scattering experiments and predicting a dominant response at specific momentum points.

Contribution

It introduces an itinerant approach incorporating orbital selectivity to explain magnetic excitations in FeSe, contrasting with previous theories.

Findings

Suppression of $(\pi,\pi)$ scattering due to orbital effects

Good match with inelastic neutron scattering data

Prediction of a $(\pi,0)$-dominated response in untwinned crystals

Abstract

Recent STM experiments and theoretical considerations have highlighted the role of interaction-driven orbital selectivity in FeSe, and its role in generating the extremely anisotropic superconducting gap structure in this material. We study the magnetic excitation spectrum resulting from the coherent quasiparticles within the same renormalized random phase approximation approach used to explain the STM experiments, and show that it agrees well with the low-energy momentum and energy dependent response measured by inelastic neutron scattering experiments. We find a correlation-induced suppression of $(\pi,\pi)$ scattering due to a small quasiparticle weight of states of $d_{xy}$ character. We compare predictions for twinned and untwinned crystals, and predict in particular a strongly $(\pi,0)$-dominated response at low energies in untwinned systems, in contrast to previous itinerant theories.