Stacking-dependent topological phase in bilayer MBi2Te4(M=Ge,Sn,Pb)

Abstract

Inspired by the breakthroughs of twisted bilayer graphene, stacking-dependent phenomena are recently emerging as fascinating objects of condensed matter research, harboring a variety of new physics. However, current studies are restricted to electronic, superconducting and magnetic properties. Here, using first-principles calculations, we reveal the connection between stacking order and topological property in bilayer $M\mathrm{B}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{4}(M=\mathrm{Ge},\mathrm{Sn},\mathrm{Pb})$. We show the stacking order determines the topological property. Upon changing the stacking order, one can achieve topological phase transition between trivial and nontrivial states. We unveil that this stacking-dependent topological property is attributed to the interlayer $\mathrm{Te}\ensuremath{-}{p}_{z}$ orbitals coupling, which is closely related to the stacking order. Our work not only expands the scope of stacking-dependent properties but also provides a promising experimental platform to study this novel stacking-dependent topological property.