Wednesday, July 31, 2013

1307.8054 (Peizhe Tang et al.)

Weak topological insulators induced by the inter-layer coupling: A
first-principles study of stacked Bi2TeI

Peizhe Tang, Binghai Yan, Wendong Cao, Shu-Chun Wu, Claudia Felser, Wenhui Duan
Based on first-principles calculations, we predict Bi2TeI, a stoichiometric compound 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 BiTeI layer plane. These Dirac cones are relatively isotropic due to the strong inter-layer coupling, distinguished from those of previously reported weak TI candidates. Moreover, with chemically stable cladding layers, the BiTeI-Bi2-BiTeI sandwiched structure is a robust quantum spin Hall system, which can be obtained by simply cleaving the bulk Bi2TeI.
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