Anomalous Landau Levels in Intrinsic Magnetic Topological Insulators

The intrinsic Magnetic Topological Insulator MnBi2Te4 (MBT) family has been extensively studied recently because of the rich physical properties it displayes in both bulk materials and thin films. The Quantum Anomalous Hall (QAH) effect has been observed in MBT thin films with an odd-number of layers in the absence of magnetic field, and quantized Hall conductivities were also reported in MBT thin films in which magnetic moments have aligned by external magnetic fields. In this talk we will discuss the electronic structure of MBT thin films in the presence of magnetic field, using a simplified effective model [1] that captures the magnetic and topological properties of the intrinsic magnetic topological insulators. We will show that in antiferromagnetic MBT thin films anomalous Landau levels play an important role in both Hall conductivity quantization [2] and in the magnetoelectric response [3]. This talk is related to the bulk theory of the magneto-electric response [4] of the same model discussed in a companion presentation by Mahon, Lei, and MacDonald.