The role of spin-flip transitions in the anomalous Hall effect of FePt alloy

TL;DR

This study uses first-principles calculations to highlight the significant role of spin-flip transitions, driven by spin-orbit interaction, in the anomalous Hall effect of FePt alloys, revealing anisotropy and the effects of substituting Pt with Pd.

Contribution

It demonstrates the importance of non-spin-conserving spin-orbit interactions and identifies spin-flip transitions as key contributors to the anomalous Hall effect in FePt.

Findings

Spin-flip transitions occur at avoided band crossings and between well-separated bands.

Replacing Pt with Pd reduces the impact of spin-orbit interactions.

A strong anisotropy in anomalous Hall conductivity is predicted due to low-frequency spin-flip transitions.

Abstract

We carry out first-principles calculations which demonstrate the importance of the non-spin-conserving part of the spin-orbit interaction for the intrinsic anomalous Hall conductivity of ordered FePt alloys. The impact of this interaction is strongly reduced if Pt is replaced by the lighter isoelectronic element Pd. An analysis of the interband transitions responsible for the anomalous velocity reveals that spin-flip transitions occur not only at avoided band crossings near the Fermi level, but also between well-separated pairs of bands with similar dispersions. We also predict a strong anisotropy in the anomalous Hall conductivity of FePt caused entirely by low-frequency spin-flip transitions.