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.