Field-free switching of spin-orbit torque in BiSb/wedge ferromagnetic structure

In this work, the micromagnetic simulation confirms that it is feasible to realize deterministic field-free switching by driving topological insulator/wedge ferromagnetic heterostructure with ultra-low current density. In addition, we studied the effects of wedge-shaped ferromagnetic layer size, interfacial Dzyaloshinskii-Moriya Interaction（DMI）, field-like torque and tilted perpendicular magnetic anisotropy off-pole angle on spin-orbit torque field-free switching. Through comprehensive optimization, the minimum critical switching current density of the topological insulator（BiSb）/wedge-shaped ferromagnetic heterostructure can be reduced to 9.0×10⁶ A/cm², which is 1～2 orders of magnitude lower than that of the traditional heavy metal/ferromagnetic structure. This research is of great significance for promoting the industrial application of low-power spin-orbit torque magnetic random-access memory.