Role of noncollinear spin texture driven z-torque in deterministic spin-orbit torque induced switching of perpendicular magnetization

Abstract

Abstract To reveal the role of chirality on field-free spin-orbit torque (SOT) induced magnetization switching, we propose an existence of z-torque through the formation of noncollinear spin texture during SOT induced magnetization switching in a laterally two-level perpendicular magnetic anisotropy (PMA) system. For torque analysis, we simulated position-dependent energy distribution, combining two-level PMA and SOT to generate noncollinear spin texture. When SOT is applied, position-dependent energy analysis uncovers z-directional torque contribution from noncollinear spin textures, rarely observed in conventional uniform SOT switching. The z-component torque is significantly influenced by the interaction between noncollinear spin texture and interfacial Dzyloshinskii-Moriya interaction of system. Furthermore, experimental results on switching current variation based on switching polarity and two-level PMA differences also closely match simulations, confirming the validity of proposed z-torque.