Nonreciprocal topological spin transport*

Superfluid-like, long-range spin transport holds promise for practical applications in low-dissipation logic and memory devices. In this study, we delve into the intriguing realm of superfluid-like spin transport facilitated by diffusion of magnetic domain walls, where chirality acts as a topological charge. This topological charge conservation leads to a gradual decay in the topological current, allowing for the transport of spin with algebraic decay over extended distances. Furthermore, we study the effects of temperature and show that increasing the temperature can trigger a transition to a regime characterized by exponential decay, driven by the presence of phase slips.

Moreover, we demonstrate the feasibility of creating a diode effect for topological currents by incorporating nonuniform Dzyaloshinskii–Moriya interactions. Notably, these concepts are not limited to this specific system but can be extended to other systems. For instance, we discuss how topologically protected excitations, such as monopoles in spin ice, can broaden the applicability of these ideas to a wider range of systems.