Analytical solution for the surface states of the antiferromagnetic topological insulator MnBi2Te4

Abstract

We analytically derive an effective model for the two-dimensional surface states of the intrinsic antiferromagnetic topological insulator MnBi2Te4 from a three-dimensional bulk Hamiltonian, including the spatial profile of the bulk magnetization. The results suggest that a diminished surface gap can arise from a smaller and more localized intralayer ferromagnetic order. We calculate the surface-state distribution and penetration depth, and derive a thin-film k·p model that exhibits an oscillating Chern number for odd and even numbers of septuple layers.