title: Quantum Phase Transition in Germanene and Stanene Bilayer: From Normal Metal to Topological Insulator.
abstract: 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.
authors.affiliation: 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.
authors.forename: Chengxi
authors.initials: C
authors.lastname: Huang
authors.affiliation: Department of Physics, Virginia Commonwealth University , Richmond, Virginia 23284, United States.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
authors.affiliation: 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.
authors.forename: Haiping
authors.initials: H
authors.lastname: Wu
authors.affiliation: 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.
authors.forename: Kaiming
authors.initials: K
authors.lastname: Deng
authors.affiliation: Department of Physics, Virginia Commonwealth University , Richmond, Virginia 23284, United States.
authors.forename: Puru
authors.initials: P
authors.lastname: Jena
authors.affiliation: 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.
authors.forename: Erjun
authors.initials: E
authors.lastname: Kan