Electrical Switching of the Edge Current Chirality in Quantum Anomalous Hall Insulators

TL;DR

This paper demonstrates the electrical switching of edge current chirality in quantum anomalous Hall insulators using spin-orbit torque, enabling control over topological states for potential applications in spintronics and quantum devices.

Contribution

It introduces a method to switch the chirality of chiral edge currents in QAH insulators via spin-orbit torque, combining experimental fabrication and theoretical analysis.

Findings

Successful switching of CEC chirality with current pulses

Quantized Hall resistance maintained before and after switching

Theoretical model confirms bulk and surface carrier contributions

Abstract

A quantum anomalous Hall (QAH) insulator is a topological state of matter, in which the interior is insulating but electrical current flows along the edges of the sample, in either clockwise (right-handed) or counter-clockwise (left-handed) direction dictated by the spontaneous magnetization orientation. Such chiral edge current (CEC) eliminates any backscattering, giving rise to quantized Hall resistance and zero longitudinal resistance. In this work, we fabricate mesoscopic QAH sandwich (i.e. magnetic topological insulator (TI)/TI/magnetic TI) Hall bar devices and succeed in switching the CEC chirality in QAH insulators through spin-orbit torque (SOT) by applying a current pulse and suitably controlled gate voltage. The well-quantized QAH states with opposite CEC chiralities are demonstrated through four- and three-terminal measurements before and after SOT switching. Our theoretical calculations show that the SOT that enables the magnetization switching can be generated by both bulk and surface carriers in QAH insulators, in good agreement with experimental observations. Current pulse-induced switching of the CEC chirality in QAH insulators will not only advance our knowledge in the interplay between magnetism and topological states but also expedite easy and instantaneous manipulation of the QAH state in proof-of-concept energy-efficient electronic and spintronic devices as well as quantum information applications.