Topological Spin Transport in Non-Collinear Antiferromagnets

Non-collinear antiferromagnets have recently received significant attention with the prediction and experimental observation of anomalous Hall effect in Mn₃X compounds [1]. In these materials, the anomalous transport is promoted by the coexistence of both non-collinear magnetic order and spin-orbit coupling. In the present work, we investigate the transport and optical properties of an antiferromagnet with non-trivial magnetic configuration in the absence of spin-orbit coupling. The model system we consider consists in a two-dimensional 3Q antiferromagnet with a texture similar to the one predicted by Kurz et al. [2] on Mn/Cu(111) interfaces. Building a minimal tight-binding model and exploiting Kubo formula, we computed the spin transport properties of the system and demonstrate that the non-trivial magnetic texture leads to topological anomalous Hall effect, as well as topological torques and damping enabling the electrical manipulation of the structure. We also show that in spite of the absence of spin-orbit coupling, this class of materials is also optically active.
[1] Nakatsuji, Nature 527, 212, (2015); Nayak et al. Sci. Adv. 2, e1501870, (2016).
[2] Kurz et al., Phys. Rev. Lett. 86, 1106 (2001).