A Magnon Band Analysis of GdRu2Si2 in the Field-Polarized State

TL;DR

This study investigates the spin excitations in GdRu2Si2's field-polarized state using neutron scattering and spin wave theory, revealing a simple bilinear Heisenberg model without higher-order interactions, informing skyrmion formation understanding.

Contribution

The paper provides a detailed magnon band analysis of GdRu2Si2, demonstrating the absence of complex exchange interactions in the field-polarized phase, contrasting with multi-Q states at lower fields.

Findings

No evidence of anisotropic or higher-order exchange terms.

Hamiltonian consistent with bilinear Heisenberg exchange.

Comparison with ab initio calculations supports simplified model.

Abstract

Understanding the formation of skyrmions in centrosymmetric materials is a problem of fundamental and technological interest. GdRu2Si2 is one such candidate material which has been shown to host a variety of multi-Q magnetic structures, including in zero-field. Here, inelastic neutron scattering is used to measure the spin excitations in the field-polarized phase of GdRu2Si2. Linear spin wave theory and a method of interaction invariant path analysis are used to derive a Hamiltonian accounting for the observed spectra, and comparisons to \textit{ab initio} calculations are made. No evidence for anisotropic or higher order-exchange terms beyond bilinear Heisenberg exchange is found. This is discussed in the context of the multi-Q states existing at lower fields, for which these types of terms have previously been conceived to be significant in the formation of multi-Q ground states.