Disorder-broadened topological Hall phase and anomalous Hall scaling in FeGe

TL;DR

This study systematically investigates how structural disorder introduced by ion irradiation affects skyrmion stability and Hall transport properties in FeGe films, revealing extended topological Hall signals and altered Hall scaling.

Contribution

It provides the first quantitative analysis of how defect density influences skyrmion phases and Hall effect mechanisms in a chiral magnet.

Findings

Disorder extends the topological Hall phase from ~200K to 4K.

Peak topological Hall signal more than doubles with disorder.

Transition from quadratic to linear Hall scaling with increased defects.

Abstract

Magnetic skyrmions are topologically protected spin textures that are promising candidates for low-power spintronic memory and logic devices. Realizing skyrmion-based devices requires an understanding of how structural disorder affects their stability and transport properties. This study uses Ne$^{+}$ ion irradiation at fluences from $10^{11}$ to $10^{14}$ ions-cm$^{-2}$ to systematically vary defect densities in 80 nm epitaxial FeGe films and quantify the resulting modifications to magnetic phase boundaries and electronic scattering. Temperature- and field-dependent Hall measurements reveal that increasing disorder progressively extends the topological Hall signal from a narrow window near 200\~K in pristine films down to 4\~K at the highest fluence, with peak amplitude more than doubling. Simultaneously, the anomalous Hall effect transitions from quadratic Berry curvature scaling to linear skew scattering behavior, with the skew coefficient increasing threefold. These results establish quantitative correlations between defect concentration, skyrmion phase space, and transport mechanisms in a chiral magnet. It demonstrates that ion-beam modification provides systematic control over both topological texture stability and electrical detectability.