Huang Chengxi, Zhou Jian, Wu Haiping, Deng Kaiming, Jena Puru, Kan Erjun
Department of Applied Physics and Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education), Nanjing University of Science and Technology , Nanjing, Jiangsu 210094, P. R. China.
Department of Physics, Virginia Commonwealth University , Richmond, Virginia 23284, United States.
J Phys Chem Lett. 2016 May 19;7(10):1919-24. doi: 10.1021/acs.jpclett.6b00651. Epub 2016 May 10.
Two-dimensional (2D) topological insulators (TIs) that exhibit quantum spin Hall effects are a new class of materials with conducting edge and insulating bulk. The conducting edge bands are spin-polarized, free of back scattering, and protected by time-reversal symmetry with potential for high-efficiency applications in spintronics. On the basis of first-principles calculations, we show that under external pressure recently synthesized stanene and germanene buckled bilayers can automatically convert into a new dynamically stable phase with flat honeycomb meshes. In contrast with the active surfaces of buckled bilayer of stanene or germanene, the above new phase is chemically inert. Furthermore, we demonstrate that these flat bilayers are 2D TIs with sizable topologically nontrivial band gaps of ∼0.1 eV, which makes them viable for room-temperature applications. Our results suggest some new design principles for searching stable large-gap 2D TIs.
呈现量子自旋霍尔效应的二维拓扑绝缘体是一类新型材料，其边缘导电而体相绝缘。导电边缘能带是自旋极化的，无背散射，并受时间反演对称性保护，在自旋电子学中具有高效应用潜力。基于第一性原理计算，我们表明在外部压力下，最近合成的锡烯和锗烯褶皱双层膜可自动转变为具有扁平蜂窝网格的新动态稳定相。与锡烯或锗烯褶皱双层膜的活性表面不同，上述新相是化学惰性的。此外，我们证明这些扁平双层膜是二维拓扑绝缘体，具有约0.1电子伏特的可观拓扑非平凡带隙，这使其适用于室温应用。我们的结果为寻找稳定的大带隙二维拓扑绝缘体提出了一些新的设计原则。
