Full Spin-Orbit Torque Switching of the Magnetic Cluster Octupole in Mn₃Sn/W Bilayer via Interface Engineering

Current-induced switching of magnetic octupoles in noncollinear antiferromagnetic (AFM) Mn₃Sn has gained much interest in the development of fast and energy-efficient magnetic memory devices. Though full switching of Mn₃Sn AFM order has been achieved in the epitaxial film prepared by molecular beam epitaxy, the switching rate (ξ) of sputtered Mn₃Sn films has been mostly limited to 40% due to crystalline imperfections. Herein, our study reports how the Mn-deficiency affects SOT switching behavior. We find that controlling Mn composition through the co-sputtering method not only eliminates secondary phases and stabilizes the Mn₃Sn phase but also naturally controls the interfacial conditions in the sputtered W/Mn₃Sn bilayers. These improvements lead to coherent crystallinity with an atomically sharper interface, resulting in 100% switching of the magnetic cluster octupole of Mn₃Sn. Our findings provide ways for optimizing the spin-orbit torque switching efficiency of Mn₃Sn-based devices.