Dislocation-driven relaxation processes at the conical to helical phase transition in FeGe

TL;DR

This study investigates how dislocation-driven relaxation processes influence the formation and stability of helimagnetic structures during the conical-to-helical phase transition in FeGe, revealing slow defect dynamics impact magnetic order.

Contribution

It combines experimental and simulation approaches to show how edge dislocations affect the nanoscale magnetic textures in chiral magnets during phase transition.

Findings

Dislocations move at about 100 m/s but cause magnetic disturbances over minutes.

Pinning by structural defects delays dislocation motion and magnetic relaxation.

Dislocation dynamics significantly influence helimagnetic domain formation.

Abstract

The formation of topological spin textures at the nanoscale has a significant impact on the long-range order and dynamical response of magnetic materials. We study the relaxation mechanisms at the conical-to-helical phase transition in the chiral magnet FeGe. By combining ac susceptibility, magnetic force microscopy measurements and micromagnetic simulations, we demonstrate how the motion of magnetic topological defects, here edge dislocations, impacts the local formation of a stable helimagnetic spin structure. Although the simulations show that the edge dislocations move with a velocity of about 100 m/s through the helimagnetic background, their dynamics are observed to disturb the magnetic order on the timescale of minutes due to pinning by randomly distributed structural defects. The results corroborate the substantial impact of dislocation motions on the nanoscale spin structure in chiral magnets, revealing previously hidden effects on the formation of helimagnetic domains and domain walls.