An Intrinsically Magnetic Topological Insulator

Abstract

When magnetism is introduced into topological insulators, time-reversal symmetry is broken and the topological gapless surface states may open a gap due to the magnetic exchange interaction. Then, various novel topological quantum states can be generated, including quantum anomalous Hall effect (QAHE) and axion insulator states, etc. Magnetic doping and magnetic proximity are believed to be useful methods to explore the interaction between topology and magnetism. However, the inhomogeneity of magnetic doping and weak interface coupling in magnetic proximity heterostructure lead to complicated magnetic order and small exchange gap. Consequently, the observed QAHE appears only at ultralow temperatures. Hence, intrinsic magnetic topological insulators (TIs) are highly desired for increasing working temperature of QAHE and further investigations on topological quantum phenomena. The realization and characterization of such systems are essential for both fundamental physics and potential technical revolutions. In this review, we briefly summarize the recent research progresses in intrinsic magnetic topological materials, mainly including antiferromagnetic TI MnBi2Te4 and its family materials.