Topologically protected magnetoresistance by quantum anomalous Hall effect

Abstract: Recently, antiferromagnetic (AF) materials have attracted rapid attention, because they are considered as outstanding candidates to replace the widely used ferromagnets in the next generation of spintronics. We propose a magnetoresistance model based on the quantum anomalous Hall effect in an AF system, which is protected by the topological Chern number. By regulating the AF exchange field and an electric field, the system can be controlled between the quantum spin Hall insulator (QSHI) phases and the quantum anomalous Hall insulator (QAHI) phases. As a result, a QAHI/QSHI/QAHI junction can be formed. In the QAHI region, the spin orientation of chiral edge state can be manipulated by tuning the AF exchange field and the electric field. Therefore, the spin directions of two QAHIs in the junction can have parallel and antiparallel configurations. The conductances of two configurations offered by chiral edge states are significantly different, and this is a magnetoresistance effect that can be electrically controlled. Because of the topological invariance, the magnetoresistance plateaus are robust to the size effect and the disorder.