Impurity-induced vector spin chirality and anomalous Hall effect in ferromagnetic metals

TL;DR

This paper proposes a new mechanism for the anomalous Hall effect in ferromagnetic metals, driven by impurity-induced vector spin chirality and skew scattering involving magnetic moments and non-magnetic impurities.

Contribution

It introduces a scattering theory approach showing how vector spin chirality around impurities causes the anomalous Hall effect in ferromagnetic metals.

Findings

Finite vector spin chirality exists around impurities in ferromagnets.

The mechanism explains temperature-dependent enhancement of the anomalous Hall effect.

Skew scattering involving two magnetic moments and an impurity is key to the effect.

Abstract

Scattering by multiple scatterers sometimes gives rise to nontrivial consequences such as anomalous Hall effect. We here study a mechanism for anomalous Hall effect which originates from the correlation of nonmagnetic impurities and localized moments; a Hall effect induced by vector spin chirality. Using a scattering theory approach, we study the skew scattering induced by the scattering processes that involve two magnetic moments and a non-magnetic impurity, which is proportional to the vector spin chirality of the spins in the vicinity of the non-magnetic impurity. Furthermore, we show that a finite vector spin chirality naturally exists around an impurity in the usual ferromagnetic metals at finite temperature due to the local inversion-symmetry breaking by the impurity. The result is potentially relevant to magnetic oxides which the anomalous Hall effect is enhanced at finite temperatures.