Influence of complex disorder on skew-scattering Hall effects in $L1_0$-ordered FePt alloy

TL;DR

This study uses first-principles calculations to show that disorder types significantly influence the skew-scattering Hall effects in FePt alloys, with implications for experimental variability.

Contribution

It reveals how different disorder types and compositions affect Hall angles in FePt, highlighting the importance of defect correlations and stoichiometry.

Findings

Hall angles depend strongly on disorder type and composition.

Short-range defect ordering can double the Hall angles.

Sign of the anomalous Hall effect changes with Fe or Pt excess.

Abstract

We show by first-principles calculations that the skew-scattering anomalous Hall and spin-Hall angles of L$1_0$-ordered FePt drastically depend on different types of disorder. A different sign of the AHE is obtained when slightly deviating from the stoichiometric ratio towards the Fe-rich side as compared to the Pt-rich side. For stoichiometric samples, short-range ordering of defects has a profound effect on the Hall angles and can change them by a factor of $2$ as compared to the case of uncorrelated disorder. This might explain the vast range of anomalous Hall angles measured in experiments, which undergo different preparation procedures and thus might differ in their crystallographic quality.