Identifying Axion Insulator by Quantized Magnetoelectric Effect in Antiferromagnetic ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ Tunnel Junction

Yu-Hang Li, Ran Cheng

Intrinsic magnetic topological insulator ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ is believed to be an axion insulator in its antiferromagnetic ground state. However, direct identifi…