On the origin of the giant SHE in Cu(Bi) alloys

TL;DR

This paper investigates the conflicting theoretical and experimental results on the giant spin Hall effect in Cu(Bi) alloys, analyzing the underlying mechanisms and differences to clarify the origin of the effect.

Contribution

The study provides a detailed analysis of existing theories and experiments, highlighting the reasons for the sign discrepancy in the spin Hall angle in Cu(Bi) alloys.

Findings

Identifies key differences between theoretical predictions and experimental measurements.

Clarifies the role of skew-scattering in the spin Hall effect.

Suggests directions for reconciling theory and experiment.

Abstract

Two years after the prediction of a giant spin Hall effect for the dilute Cu(Bi) alloy [Gradhand et al., Phys. Rev. B 81, 245109 (2010)], a comparably strong effect was measured in thin films of Cu(Bi) alloys by Niimi et al. [Phys. Rev. Lett. 109, 156602 (2012)]. Both theory and experiment consider the skew-scattering mechanism to be responsible, however they obtain opposite sign for the spin Hall angle. Based on a detailed analysis of existing theoretical results, we explore differences between theory and experiment.