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arXiv · 1405.3823

Large-Gap Quantum Spin Hall Insulator in single layer bismuth monobromide Bi$_{4}$Br$_{4}$

Jin-Jian Zhou·Wanxiang Feng·Cheng-Cheng Liu·Shan Guan·Yugui Yao
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Abstract

Quantum spin Hall (QSH) insulators have gapless topological edge states inside the bulk band gap, which can serve as dissipationless spin current channels protected by the time-reversal symmetry. The major challenge currently is to find suitable materials for this topological state. Here, we predict a new large-gap QSH insulator with bulk direct band gap of $\sim$0.18 eV, in single-layer Bi$_{4}$Br$_{4}$, which could be exfoliated from its three-dimensional bulk material due to the weakly-bonded layered structure. The band gap of single-layer Bi$_{4}$Br$_{4}$ is tunable via strain engineering, and the QSH phase is robust against external strain. In particular, because this material consists of special one-dimensional molecular chain as its basic building block, the single layer Bi$_{4}$Br$_{4}$ could be easily torn to ribbons with clean and atomically sharp edges, which are much desired for the observation and application of topological edge states. Our work thus provides a new promising material for experimental studies and practical applications of QSH effect.

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Jin-Jian Zhou, Wanxiang Feng, Cheng-Cheng Liu, Shan Guan, Yugui Yao. 2015-06-05. Large-Gap Quantum Spin Hall Insulator in single layer bismuth monobromide Bi$_{4}$Br$_{4}$. https://doi.org/10.1021/nl501907g

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