Néel vector switching by magnetization-dependent layer-resolved spin-orbit torque

Abstract

Layer-resolved spin-orbit torques offer a route to controlling antiferromagnetic order through local spin-charge conversion. First-principles calculations show that the layer-resolved spin Hall conductivity of the antiferromagnetic topological insulator $\mathrm{Mn}{\mathrm{Bi}}_2{\mathrm{Te}}_4$ consists of a magnetization-independent spin Hall term plus two spin anomalous Hall terms that are even in the Néel vector yet evolve with the local magnetic order, while local inversion asymmetry differentiates surface and inner layers. This response enables reversible, field-free switching of the Néel vector in finite-septuple-layer films. Although the magnetization-independent spin Hall term alone can reverse the order, the spin anomalous Hall terms provide magnetization-dependent feedback that redistributes the layer-resolved torques and reshapes the switching trajectory, offering a route to tailoring current-driven switching through layer and interface engineering.