November 07, 2022
Minneapolis, United States
Identifying Axion Insulator by Quantized Magnetoelectric Effect in Antiferromagnetic MnBi2Te4 Tunnel Junction
Intrinsic magnetic topological insulator MnBi2Te4 is believed to be an axion insulator in its antiferromagnetic ground state. However, direct identification of axion insulators remains experimentally elusive because the observed large resistance and the vanishing Hall effect, while indicating the onset of the axion field, is inadequate to distinguish the system from a trivial normal insulator. Using Green's function method, we theoretically demonstrate the quantized topological magnetoelectric current in a tunnel junction with atomically thin MnBi2Te4 sandwiched between two metalic contacts, which is a smoking-gun signal that unambiguously confirms antiferromagnetic MnBi2Te4 to be an axion insulator. Our predictions can be verified directly by experiments.
References Yu-Hang Li and Ran Cheng, Identifying Axion Insulator by Quantized Magnetoelectric Effect in Antiferromagnetic MnBi2Te4 Tunnel Junction. arXiv:2111.11500