Ultralong octupole moment switching driven by twin topological spin structures.

Abstract

Spintronics has emerged as a revolutionary frontier in the pursuit of faster, more energy-efficient, and technologically advanced electronics. However, the transmission distance of conventional ferromagnetic spin-orbit torque is typically limited to <10 nm, posing a critical challenge for spin current transport. Here we grow Mn₃Sn films with a 30° canted magnetic octupole moment oriented out of plane, in which the Kagome spin structure is fully perpendicular to the film surface. By introducing a spin-orbital coupled amorphous Pt overlayer, we demonstrate the electrical switching dynamics of magnetic octupoles in Kagome antiferromagnetic Mn₃Sn. Remarkably, perpendicular spin currents reverse Mn₃Sn layers up to 60 nm thick. The switching efficiency of Mn₃Sn/Pt bilayers increases with antiferromagnetic thickness, peaking near 40 nm before decreasing, reflecting a long spin diffusion length sustained by twin topological spin structures. Direct observation of magnetic octupole dynamics further validates the presence of such twin spin orders. Moreover, our theoretical analysis reveals that twin topological spin canting intrinsically supports ultralong-distance octupole switching. These findings establish antiferromagnetic Mn₃Sn as a robust platform for efficient spin transport and highlight the pronounced long-range nature of spin-orbit torque enabled by twin spin order.