Nonlinear spin Hall effect in $\mathcal{PT}$-symmetric collinear magnets

TL;DR

This paper theoretically explores a nonlinear spin Hall effect in $ ext{PT}$-symmetric antiferromagnetic metals, revealing a spin-dependent Berry curvature dipole as its microscopic origin, independent of spin-orbit coupling or uniform magnetization.

Contribution

It introduces a microscopic model explaining the nonlinear spin Hall effect in $ ext{PT}$-symmetric magnets without relying on spin-orbit coupling or magnetization, and provides a classification table for candidate materials.

Findings

Nonlinear spin Hall effect arises from a spin-dependent Berry curvature dipole.

The effect can occur without relativistic spin-orbit coupling or uniform magnetization.

A comprehensive table links magnetic multipoles, spin conductivity, and materials.

Abstract

We theoretically investigate a nonlinear spin Hall effect in $\mathcal{PT}$-symmetric antiferromagnetic metals, which serve as an efficient spin current generator. We elucidate that an emergent spin-dependent Berry curvature dipole is a microscopic origin of the nonlinear spin Hall effect, which becomes nonzero with neither relativistic spin-orbit coupling, uniform magnetization, nor spin-split band structure. By analyzing a microscopic antiferromagnetic model without spin-orbit coupling for an intuitive understanding of the phenomena, we elucidate essential hopping processes and a condition to enhance the nonlinear spin Hall conductivity. We also provide a complete table to include useful correspondence among the N\'eel vector, odd-parity multipoles, nonlinear spin conductivity tensor, and candidate materials in all the $\mathcal{PT}$-symmetric black-and-white magnetic point groups.