Giant Extrinsic Spin Hall Effect due to Rare-Earth Impurities

TL;DR

This paper demonstrates that rare-earth impurities like Ce and Yb can induce a giant extrinsic spin Hall effect in metals, primarily through skew scattering, with potential for significant spintronic applications.

Contribution

It provides a theoretical analysis of the extrinsic spin Hall effect caused by rare-earth impurities, highlighting the dominant skew scattering mechanism and quantifying the spin Hall angle.

Findings

Skew scattering dominates over side jump in dilute impurity limit.

Spin Hall angle can reach about 0.1 with certain phase shifts.

Large orbital angular momentum in rare-earth impurities enhances the effect.

Abstract

We investigate the extrinsic spin Hall effect in the electron gas model due to magnetic impurities, by focusing on Ce- and Yb-impurities. In the dilute limit, the skew scattering term dominates the side jump term. For Ce-impurities, the spin Hall angle $\alpha_{\rm SH}$ due to skew scattering is given by $-8\pi\sin\delta_2/7$, where $\delta_2 (\ll 1)$ is the phase shift for$d (l=2)$ partial wave. Since $\alpha_{\rm SH}$ reaches $O(10^{-1})$ if $\delta_2 \simge 0.03$, the spin Hall effect is anticipated to be considerable in metals with rare-earth impurities. The giant extrinsic SHE originates from the large orbital angular momentum, which is also significant for the intrinsic SHE.