Stable two-dimensional dumbbell stanene: A quantum spin Hall insulator

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From density functional theory within the generalized gradient approximation we predict a structure of stanene with dumbbell units (DBs), and show that it is a two-dimensional topological insulator with an inverted band gap which can be tuned by compressive strain. Furthermore, we propose that the boron nitride sheet and reconstructed (2x2) InSb(111) surfaces are ideal substrates for the experimental realization of DB stanene, maintaining its nontrivial topology. Combined with standard semiconductor technologies, such as magnetic doping and electrical gating, the quantum anomalous Hall effect, Chern half metallicity, and topological superconductivity can be realized in DB stanene on those substrates. These properties make the two-dimensional supported stanene a good platform for the study of quantum spin Hall insulators as well as other exotic quantum states of matter.
We acknowledge support from the Ministry of Science and Technology of China (Grants No. 2011CB606405 and No. 2011CB921901) and the National Natural Science Foundation of China (Grant No. 11334006). A.R., S.C., and L.X. acknowledge financial support from the European Research Council Grant DYNamo (ERC-2010-AdG No. 267374) Spanish Grants (FIS2010-21282-C02-01), Grupos Consolidados UPV/EHU del Gobierno Vasco (IT578-13), and EC project CRONOS (280879-2 CRONOS CP-FP7.