Pressure-induced topological quantum phase transition in the magnetic topological insulator MnBi2Te4

Abstract

In this paper, topological quantum phase transition was reported in the magnetic topological insulator MnBi2Te4 under pressure strain. Electronic and topological properties of the bulk anti-ferromagnetic MnBi2Te4 were investigated by first-principles calculations. We found that the band structure of MnBi2Te4 changes with the strain, resulting in a phase transition between metal and insulator. From the variation of charge-density distribution with strain, it was found that hydrostatic tensile strain is beneficial for increasing the interlayer spacing, thereby reducing the anti-ferromagnetic interaction between layers. On the contrary, the compressive strain promotes the strengthening of the bonding between the Te and Bi atomic layers. It was worth noting that the phase transition occurs at 2.12% strain when the band crossing is observed at Γ point, suggesting that the band gap has just closed. In addition, through the calculation of surface states, it is observed that, after the action of 2.12% strain, the bulk band gap of the system closes with the surface band gap reopens, achieving an intrinsic mechanism of strain modulation of the MnBi2Te4 antiferromagnetic bulk structure to undergoes a topological quantum phase transition. Our results provide feasible guidance not only for pressure-strain engineering of MnBi2Te4 experimentally but also for developing a meaningful strain-control mechanism for the electronic structures of other potential intrinsic magnetic insulators.