Spin-orbit torque-driven chiral domain wall motion in Mn3Sn

Abstract

Non-collinear chiral antiferromagnets, such as Mn3X (X = Sn, Ge), have garnered significant interest in spintronics due to their topologically protected Weyl nodes and large momentum-space Berry curvatures. In this study, we report rapid chirality domain wall (CDW) motion in Mn3Sn, driven by spin-orbit torque at over 545.3 m s−1 under a remarkably low current density of 9 × 1010 A m−2. The results demonstrate that the chirality of the domain wall and the direction of the current collectively determine the displacement direction of the CDW. Theoretically, we provide an analysis of the effective field experienced by the octupole moment, uncovering the underlying motion mechanism based on the unique profile of the chiral spin structure. Notably, CDWs with opposite chirality can coexist within the same sample containing the Dzyaloshinskii–Moriya interaction, where the formation of a Néel-like CDW is governed by the orientation of the kagome plane, rather than by the negligible magnetostatic energy of the small net magnetization. Additionally, the CDW, with a considerable width of 770 nm, is segmented into three 60° portions due to the sixfold anisotropy in Mn3Sn. These emphasize that CDW motion in Mn3Sn cannot be quantitatively studied using ferromagnetic frameworks. We also demonstrate that a small external field can effectively regulate CDW velocity. Our comprehensive results and theoretical analysis provide crucial guidelines for integrating antiferromagnet CDWs into functional spintronic devices.