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First-principles prediction on bismuthylene monolayer as a promising quantum spin Hall insulator

Abstract

Two-dimensional (2D) large band-gap topological insulators (TIs) with high stable structure are imperative for achieving dissipationless transport devices. However, up to now, only very few materials have been observed experimentally to host quantum spin Hall (QSH) effect at low temperature, thus obstructs their potential application in practice. By using first-principles calculations, here we predict a new 2D TI in the porous allotrope of Bismuth monolayer, i.e. bismuthylene, its geometric stability being confirmed by phonon spectrum and molecular dynamics simulations. The analyses of electronic structures reveal that it is a native QSH state with a gap much as large as 0.28 eV at the Γ point, which is larger than the buckled Bi (111) (0.2 eV) and suit for room temperature applications. Notably, it has a much lower energy than buckled Bi (111) and flattened Bi films, thus it is feasible to the experimental realization. Interestingly, the topological properties can be reserved under strains within -6 ~ 3 % and electric fields up to 0.8 eV/Å. A heterostructure by sandwiching bismuthylene between BN sheets has been constructed and revealed that the nontrivial topology of bismuthylene remains with a sizable band gap. These findings provide a platform to design a large-gap QSH insulator based on the 2D bismuthylene films, which show potential applications in spintronics devices.

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Publication details

The article was received on 21 Mar 2017, accepted on 15 May 2017 and first published on 16 May 2017


Article type: Paper
DOI: 10.1039/C7NR01992K
Citation: Nanoscale, 2017, Accepted Manuscript
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    First-principles prediction on bismuthylene monolayer as a promising quantum spin Hall insulator

    R. Zhang, C. Zhang, W. Ji, S. Yan and Y. Yao, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR01992K

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