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Abstract:
Based on first-principles calculations, we predict Bi2TeI, a
stoichiometric compound that is synthesized, to be a weak topological
insulator (TI) in layered subvalent bismuth telluroiodides. Within a
bulk energy gap of 80 meV, two Dirac-cone-like topological surface
states exist on the side surface perpendicular to the BiTeI layer plane.
These Dirac cones are relatively isotropic due to the strong interlayer
coupling, distinguished from those of previously reported weak TI
candidates. Moreover, with chemically stable cladding layers, the
BiTeI-Bi-2-BiTeI sandwiched structure is a robust quantum spin Hall
system, which can be obtained by simply cleaving the bulk Bi2TeI.
