Spin-Orbit Torque Switching of the Edge State Chirality in Quantum Anomalous Hall Insulators

A quantum anomalous Hall (QAH) insulator is a topological state of matter, which processes the quantized Hall resistance and dissipationless chiral edge current (CEC) without the need for an external magnetic field. CEC flows along the edges of the sample in either a clockwise or counter-clockwise direction dictated by the spontaneous magnetization direction. To date, the chirality of CEC in QAH insulators can be only controlled by sweeping back and forth the external magnetic field. However, this is clumsy and cumbersome as a means to operate in real CEC-based electronic devices. In this work, we fabricate mesoscopic QAH sandwich Hall bar devices with a width of 1~10 μm and succeed in switching the CEC chirality in QAH insulators through spin-orbit torque (SOT) by applying a current pulse under a suitably controlled gate voltage. Since the SOT magnetization switching ratio is easily greater than the quantum percolation threshold of magnetic domains, the well-quantized QAH state with the opposite CEC chirality can appear after the magnetization switching. The realization of SOT switching of the edge state chirality in QAH insulators will not only advance our knowledge of the interplay between magnetism and topological states but also expedite easy and instantaneous manipulation of the QAH state in energy-efficient electronic and spintronic devices as well as quantum information applications.