期刊
NANO RESEARCH
卷 8, 期 9, 页码 2954-2962出版社
TSINGHUA UNIV PRESS
DOI: 10.1007/s12274-015-0800-4
关键词
two-dimensional monolayers; topological insulators; quantum spin Hall effect; Rashba-Dresselhaus effect; density functional theories
类别
资金
- National Basic Research Program of China (973 program) [2013CB632401]
- National Natural Science Foundation of China [21333006, 11174180]
- Fund for Doctoral Program of National Education [20120131110066]
- Natural Science Foundation of Shandong Province [ZR2013AM021]
- 111 Project [B13029]
A new family of two-dimensional (2D) topological insulators (TIs) comprising g-TlA (A = N, P, As, and Sb) monolayers constructed by Tl and group-V elements is predicted by first-principles calculations and molecular-dynamics (MD) simulations. The geometric stability, band inversion, nontrivial edge states, and electric polarity are investigated to predict the large-gap quantum spin Hall insulator and Rashba-Dresselhaus effects. The MD results reveal that the g-TlA monolayers remain stable even at room temperature. The g-TlA (A = As, Sb) monolayers become TIs under the influence of strong spin-orbit couplings with large bulk bandgaps of 131 and 268 meV, respectively. A single band inversion is observed in each g-TlA (A = As, Sb) monolayer, indicating a nontrivial topological nature. Furthermore, the topological edge states are described by introducing a sufficiently wide zigzag-nanoribbon. A Dirac point in the middle of the bulk gap connects the valence- and conduction-band edges. The Fermi velocity near the Dirac point with a linear band dispersion is similar to 0.51 x 10(6) m/s, which is comparable to that of many other 2D nanomaterials. More importantly, owing to the broken inversion symmetry normal to the plane of the g-TlA films, a promising Rashba-Dresselhaus effect with the parameter up to 0.85 eV center dot is observed in the g-TlA (A = As, Sb) monolayers. Our findings regarding 2D topological g-TlA monolayers with room-temperature bandgaps, intriguing topological edge states, and a promising Rashba-Dresselhaus effect are of fundamental value and suggest potential applications in nanoelectronic devices.
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