AC current-driven magnetization switching and nonlinear Hall rectification in a magnetic topological insulator

Spin-orbit torque arising from the surface states of topological insulators enables efficient current-induced control of magnetization. In this presentation, we demonstrate alternating-current (AC) driven magnetization reversal in a semi-magnetic topological insulator (Cr,Bi,Sb)2Te3/(Bi,Sb)2Te3, facilitated by a low threshold current density of 1.5x10^9 A/m^2. Time-domain Hall voltage measurements using an oscilloscope reveal a strongly nonlinear Hall response during the magnetization reversal process. Fourier analysis of the time-varying Hall voltage identifies higher-harmonic signals and a rectified direct-current (DC) component, highlighting the complex interplay among the applied current, external magnetic field, and magnetization dynamics. Furthermore, the hysteretic current-voltage characteristics gives rise to frequency mixing under dual-frequency excitation. This effect, distinct from conventional polynomial-based nonlinearities, allows for selective extraction of specific frequency components. Our results demonstrate that AC-driven switching produces tunable nonlinear responses, offering a new pathway for multifunctional spintronic devices with potential applications in energy-efficient memory, signal processing, and frequency conversion.