Tuning spin currents in collinear antiferromagnets and altermagnets

TL;DR

This paper demonstrates how to induce and control spin currents in collinear antiferromagnets and altermagnets using symmetry-breaking techniques like electric fields and strain, enabling efficient low-power spintronics.

Contribution

It introduces a symmetry-based framework to generate spin currents in materials previously thought incapable, using phase transitions driven by external stimuli.

Findings

Finite spin currents can be induced via symmetry-lowering phase transitions.

Charge-to-spin conversion ratios can reach up to 100%.

The approach is validated with density functional theory and transport calculations.

Abstract

Spin current generation through non-relativistic spin splittings, found in uncompensated magnets and d-wave altermagnets, is desirable for low-power spintronics. Such spin currents, however, are symmetry forbidden in conventional collinear antiferromagnets and higher-order altermagnets. Using spin point group analysis, we demonstrate that finite spin currents can be induced in these materials via magnetoelectric, piezomagnetic, and piezomagnetoelectric-like couplings. We utilize electric fields, strain, and their combinations to drive symmetry-lowering phase transitions into uncompensated magnetic or d-wave altermagnetic states, thereby enabling finite spin conductivity in a broader class of magnetic materials. We further substantiate this framework using density functional theory and Boltzmann transport calculations on representative magnetic materials - KV2Se2O, RuF4 , Cr2O3 , FeS2 , and MnPSe3 - spanning these different cases. The charge-to-spin conversion ratio reaches up to almost 100% via uncompensated magnetism and about 40% via d-wave altermagnetism under realistic conditions, highlighting the effectiveness of this approach for efficient spin current generation.