Magnetoresistance Anomalies in (Ga,Mn)As Epilayers with Perpendicular Magnetic Anisotropy

TL;DR

This study identifies antisymmetric anomalies in the magnetoresistance of (Ga,Mn)As epilayers with perpendicular magnetic anisotropy, linked to domain wall effects during magnetization reversal.

Contribution

It demonstrates that anomalous Hall effect contributions cause antisymmetric magnetoresistance spikes during magnetization reversal in (Ga,Mn)As epilayers.

Findings

Anomalies occur during magnetization reversal.

Anomalies are linked to domain walls and Hall effect contributions.

Antisymmetric dependence on field sweep helicity.

Abstract

We report the observation of anomalies in the longitudinal magnetoresistance of tensile-strained (Ga,Mn)As epilayers with perpendicular magnetic anisotropy. Magnetoresistance measurements carried out in the planar geometry (magnetic field parallel to the current density) reveal "spikes" that are antisymmetric with respect to the direction of the magnetic field. These anomalies always occur during magnetization reversal, as indicated by a simultaneous change in sign of the anomalous Hall effect. The data suggest that the antisymmetric anomalies originate in anomalous Hall effect contributions to the longitudinal resistance when domain walls are located between the voltage probes. This interpretation is reinforced by carrying out angular sweeps of $\vec{H}$, revealing an antisymmetric dependence on the helicity of the field sweep.