Position-dependent Voltage-controlled Switching of Perpendicular Ferromagnet on a Topological Insulator: A Micromagnetic Simulation Study

Magnetization switching dynamics of a perpendicular magnetic anisotropy (PMA) ferromagnetic metal (FM) on the surface of a topological insulator (TI) have been analyzed through micromagnetic simulations. The current shunting in the TI-FM bilayer makes the spin torque as well as the potential in the FM to be position-dependent. Hence, position-dependent voltage-controlled magnetic anisotropy (VCMA) is used to achieve the field-free switching of the FM using the position-dependent spin torque from the underlying TI. Simulations are performed to obtain the behavior of the switching time as a function of VCMA pulse ON time by varying other parameters of interest, like the normalized tunneling rate across the interface of the TI and FM bilayer, the damping like torque coefficient in the FM, the applied voltage for VCMA, and the current density on the TI surface.