Controlling spin current polarization through non-collinear antiferromagnetism

TL;DR

This paper demonstrates that non-collinear antiferromagnetic Mn$_{3}$GaN can be used to control the polarization direction of spin currents, enabling unconventional spin-orbit torques for advanced spintronic applications.

Contribution

It introduces a novel method of controlling spin current polarization via non-collinear antiferromagnetic structures, expanding the possibilities for spin-orbit torque manipulation.

Findings

Unconventional spin polarizations collinear to charge or spin currents observed.

Epitaxial Mn3GaN/Permalloy heterostructures generate unique spin Hall torques.

Control of spin polarization direction achieved through spin-structure design.

Abstract

The spin-Hall effect describes the interconversion of charge currents and spin currents, enabling highly efficient manipulation of magnetization for spintronics. Symmetry conditions generally restrict polarizations of these spin currents to be orthogonal to both the charge and spin flows. Spin polarizations can deviate from such direction in nonmagnetic materials only when the crystalline symmetry is reduced11. Here we experimentally show control of the spin polarization direction by using a non-collinear antiferromagnet Mn$_{3}$GaN, in which the triangular spin structure creates a low magnetic symmetry state while maintaining a high crystalline symmetry. We demonstrate that epitaxial Mn3GaN/Permalloy heterostructures can generate unique types of spinHall torques at room temperature corresponding to unconventional spin polarizations collinear to spin currents or charge currents which are forbidden in any sample with two-fold rotational symmetry. Our results demonstrate an approach based on spin-structure design for controlling spinorbit torque, paving the way for further progress in the emergent field of antiferromagnetic spintronics.