期刊
NPG ASIA MATERIALS
卷 6, 期 -, 页码 -出版社
NATURE RESEARCH
DOI: 10.1038/am.2014.113
关键词
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资金
- MOST Project of China [2010CB833104, 2014CB920903, 2011CBA00100, 2013CB932604]
- National Natural Science Foundation of China [51371009, 51171001, 11174337, 11225418, 50971003, 11274016]
- National High Technology Research and Development Program of China [2011AA03A403]
- Specialized Research Fund for the Doctoral Program of Higher Education of China [20121101110046, 20130001110002]
- Excellent Young Scholars Research Fund of the Beijing Institute of Technology [2013YR1816]
A large bulk band gap is critical for the application of quantum spin Hall (QSH) insulators or two-dimensional (2D) topological insulators (TIs) in spintronic devices operating at room temperature (RT). On the basis of first-principles calculations, we predicted a group of 2D TI BiX/SbX (X = H, F, Cl and Br) monolayers with extraordinarily large bulk gaps from 0.32 eV to a record value of 1.08 eV. These giant-gaps are entirely due to the result of the strong spin-orbit interaction related to the p(x) and p(y) orbitals of the Bi/Sb atoms around the two valleys K and K' of the honeycomb lattice, which is significantly different from that consisting of the p(z) orbital as in graphene/silicene. The topological characteristic of BiX/SbX monolayers is confirmed by the calculated nontrivial Z(2) index and an explicit construction of the low-energy effective Hamiltonian in these systems. We demonstrate that the honeycomb structures of BiX monolayers remain stable even at 600 K. Owing to these features, the giant-gap TIs BiX/SbX monolayers are an ideal platform to realize many exotic phenomena and fabricate new quantum devices operating at RT. Furthermore, biased BiX/SbX monolayers become a quantum valley Hall insulator, exhibiting valley-selective circular dichroism.
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