# AC Current‐Driven Magnetization Switching and Nonlinear Hall Rectification in a Magnetic Topological Insulator

## TL;DR

This paper shows how AC currents can efficiently switch magnetization in a topological insulator and produce nonlinear Hall effects, useful for spintronic devices.

## Contribution

Demonstrates AC-driven magnetization reversal with low current density and nonlinear Hall rectification in a magnetic topological insulator.

## Key findings

- AC current enables magnetization reversal with a low threshold current density of 1.5 × 10⁹ A m⁻².
- Nonlinear Hall rectification and higher-harmonic signals are observed during magnetization reversal.
- Hysteretic behavior leads to asymmetric frequency mixing under dual-frequency excitation.

## Abstract

Spin–orbit torque arising from the spin–orbit‐coupled surface states of topological insulators enables current‐induced control of magnetization with high efficiency. Here, alternating‐current (AC) driven magnetization reversal is demonstrated in a semi‐magnetic topological insulator (Cr,Bi,Sb)2Te3/(Bi,Sb)2Te3, facilitated by a low threshold current density of 1.5 × 109 A m−2. Time‐domain Hall voltage measurements using an oscilloscope reveal a strongly nonlinear and rectified 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, a hysteretic behavior in the 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. The results demonstrate that AC excitation can not only switch magnetization efficiently but also induce tunable nonlinear responses, offering a new pathway for multifunctional spintronic devices with potential applications in energy‐efficient memory, signal processing, and frequency conversion.

This study reports alternating‐current (AC) driven magnetization reversal in a semi‐magnetic topological insulator (Cr,Bi,Sb)2Te3/(Bi,Sb)2Te3, with low current density. Time‐domain Hall voltage measurements reveal a nonlinear and rectified Hall effect, along with higher‐harmonic responses and hysteresis. These findings, including asymmetric frequency mixing, offer potential for spintronic applications like signal processing and frequency conversion.