Anomalous Hall magnetoresistance in a ferromagnet

TL;DR

This paper reports the experimental discovery of anomalous Hall magnetoresistance in ferromagnets, revealing a new spin current-related effect that could advance spintronic device research.

Contribution

It introduces the concept of anomalous Hall magnetoresistance and demonstrates its occurrence in various ferromagnetic samples, expanding understanding of charge-spin conversion mechanisms.

Findings

Anomalous Hall magnetoresistance exhibits the same angular dependence as spin Hall magnetoresistance.

The effect is observed in multiple ferromagnetic and multilayer samples.

Results are analyzed using the drift-diffusion model.

Abstract

The anomalous Hall effect, observed in conducting ferromagnets with broken time-reversal symmetry, offers the possibility to couple spin and orbital degrees of freedom of electrons in ferromagnets. In addition to charge, the anomalous Hall effect also leads to spin accumulation at the surfaces perpendicular to both the current and magnetization direction. Here we experimentally demonstrate that the spin accumulation, subsequent spin backflow, and spin-charge conversion can give rise to a different type of spin current related magnetoresistance, dubbed here as the anomalous Hall magnetoresistance, which has the same angular dependence as the recently discovered spin Hall magnetoresistance. The anomalous Hall magnetoresistance is observed in four types of samples: co-sputtered (Fe1-xMnx)0.6Pt0.4, Fe1-xMnx and Pt multilayer, Fe1-xMnx with x = 0.17 to 0.65 and Fe, and analyzed using the drift-diffusion model. Our results provide an alternative route to study charge-spin conversion in ferromagnets and to exploit it for potential spintronic applications.