MnBi2Te4 – a good platform for topological quantum physics study

Abstract

Magnetic topological insulator MnBi2Te4 is an intrinsic van der Waals layer structure compound. The interplay between magnetism and topology makes MnBi2Te4 a good platform to investigate controllable topological phase transition and emerging physical states such as quantum anomalous Hall state and Weyl semimetal phase. Crystal characterization showed a rhombohedral unit cell composing of Te-Bi-Te-Mn-Te-Bi-Te septuple layer (SL) coupled antiferromagnetically. Systematically investigation of surface states with angle-resolved photoemission spectroscopy and of bulk states with transport measurement showed detailed electronic structure of MnBi2Te4 crystal. Rich topological phases were observed in MnBi2Te4. Temperature, doping and external magnetic field could affect the different topological phases and induce phase transitions in certain conditions. Quantum anomalous Hall effect (QAHE) was realized at as high as 6.5 K in 5-SLs MnBi2Te4 flake. Furthermore, the negative to positive magnetoresistance transition and the thickness dependent QAHE Chern number of MnBi2Te4 provide strong evidences for the Weyl semimetal states in this material. Based on experiments done from 2019 to 2022, our review should shed light on future research opportunities on MnBi2Te4 compound.