Generation of Spin Currents by Magnetic Field in $\mathcal{T}$- and $\mathcal{P}$-Broken Materials

TL;DR

This paper predicts that magnetic fields can generate pure spin currents in certain symmetry-broken metals, offering a new mechanism for spintronics applications, supported by theoretical models and candidate materials.

Contribution

It introduces a novel theoretical prediction of magnetic-field-induced spin currents in $ ext{T}$- and $ ext{P}$-broken materials with $ ext{PT}$ symmetry, expanding spin current generation mechanisms.

Findings

Magnetic fields induce spin currents without charge currents in specific symmetry conditions.

The effect is demonstrated in a minimal model of an antiferromagnetic Dirac semimetal.

Candidate materials include topological antiferromagnetic Dirac semimetals and Weyl semimetals.

Abstract

Pure spin currents carry information in quantum spintronics and could play an essential role in the next generation low-energy-consumption electronics. Here we theoretically predict that the magnetic field can induce a quantum spin current without a concomitant charge current in metals without time reversal symmetry $\mathcal{T}$ and inversion symmetry $\mathcal{P}$ but respect the combined $\mathcal{PT}$ symmetry. It is governed by the magnetic moment of the Bloch states on the Fermi surface, and can be regarded as a spinful generalization of the gyrotropic magnetic effect in $\mathcal{P}$-broken metals. The effect is explicitly studied for a minimal model of an antiferromagnetic Dirac semimetal, where the experimental signature is proposed. We further propose candidate materials, including topological antiferromagnetic Dirac semimetals, Weyl semimetals, and tenary Heusler compounds.