Anomalous Pinning Fields in Helical Magnets: Screening of the Quasiparticle Interaction

TL;DR

This paper investigates the discrepancy in spin-orbit interaction strength measurements in helical magnets, revealing that screening effects in the fermionic theory reconcile differences between experimental observables.

Contribution

It introduces a fermionic theory approach to account for screening effects, resolving the discrepancy in spin-orbit coupling estimates in helical magnets.

Findings

Screening effects significantly alter the effective electron-electron interaction.

Fermionic theory explains the factor of 20 discrepancy in g_so values.

Standard LGW theory alone is insufficient without considering fermionic screening.

Abstract

The spin-orbit interaction strength g_so in helical magnets determines both the pitch wave number q and the critical field H_c1 where the helix aligns with an external magnetic field. Within a standard Landau-Ginzburg-Wilson (LGW) theory, a determination of g_so in MnSi and FeGe from these two observables yields values that differ by a factor of 20. This discrepancy is remedied by considering the fermionic theory underlying the LGW theory, and in particular the effects of screening on the effective electron-electron interaction that results from an exchange of helical fluctuations.