Gigantic Anisotropy of Self-Induced Spin-Orbit Torque in Weyl Ferromagnet Co2MnGa

TL;DR

This paper reports a giant anisotropic self-induced spin-orbit torque in Weyl ferromagnet Co2MnGa, driven by topological electronic states and strain, challenging conventional symmetry expectations and enabling new spintronic applications.

Contribution

It reveals a gigantic anisotropic self-induced SOT in Co2MnGa with sign inversion, linked to topological states and strain modulation, advancing understanding of SOT physics.

Findings

Gigantic anisotropy of self-induced SOT observed.

Sign inversion of SOT depending on crystal axes.

SOT magnitude comparable to heavy metal/ferromagnet systems.

Abstract

Spin-orbit torque (SOT) is receiving tremendous attention from both fundamental and application-oriented aspects. Co2MnGa, a Weyl ferromagnet that is in a class of topological quantum materials, possesses cubic-based high structural symmetry, the L21 crystal ordering, which should be incapable of hosting anisotropic SOT in conventional understanding. Here we show the discovery of a gigantic anisotropy of self-induced SOT in Co2MnGa. The magnitude of the SOT is comparable to that of heavy metal/ferromagnet bilayer systems despite the high inversion symmetry of the Co2MnGa structure. More surprisingly, a sign inversion of the self-induced SOT is observed for different crystal axes. This finding stems from the interplay of the topological nature of the electronic states and their strong modulation by external strain. Our research enriches the understanding of the physics of self-induced SOT and demonstrates a versatile method for tuning SOT efficiencies in a wide range of materials for topological and spintronic devices.