Tunneling spin Hall effect induced by unconventional $p$-wave magnetism

TL;DR

This paper predicts a tunneling spin Hall effect in a junction involving a $p$-wave magnet, where spin-dependent Andreev reflection generates a pure transverse spin current with high efficiency, relevant for spintronics.

Contribution

It introduces a novel tunneling spin Hall effect induced by unconventional $p$-wave magnetism and provides an analytical framework for understanding its dependence on Fermi surface splitting.

Findings

Spin-dependent Andreev reflection causes a transverse spin current.

The spin Hall effect is governed by the Fermi surface splitting direction.

Large spin Hall angle indicates efficient charge-to-spin conversion.

Abstract

We propose a tunneling spin Hall effect in a normal metal/$p$-wave magnet/superconductor junction. It is found that the Andreev reflection in the normal lead is spin-dependent and exhibits strong asymmetry with respect to the transverse momentum, giving rise to a pure transverse spin Hall current with zero net charge. The transverse spin conductance is analytically derived using the nonequilibrium Green's function approach, revealing that the predicted spin Hall effect is governed by the direction of the Fermi surface splitting in the $p$-wave magnet. A finite transverse spin current with a large spin Hall angle arises when the line connecting the centers of the spin-split Fermi surfaces is perpendicular to the normal direction of the junction, which indicates a highly efficient charge-to-spin conversion, suggesting potential applications in spintronic devices.