title: Room Temperature Quantum Spin Hall Insulator in Ethynyl-Derivative Functionalized Stanene Films.
abstract: Quantum spin Hall (QSH) insulators feature edge states that topologically protected from backscattering. However, the major obstacles to application for QSH effect are the lack of suitable QSH insulators with a large bulk gap. Based on first-principles calculations, we predict a class of large-gap QSH insulators in ethynyl-derivative functionalized stanene (SnC2X; X = H, F, Cl, Br, I), allowing for viable applications at room temperature. Noticeably, the SnC2Cl, SnC2Br, and SnC2I are QSH insulators with a bulk gap of ~0.2 eV, while the SnC2H and SnC2F can be transformed into QSH insulator under the tensile strains. A single pair of topologically protected helical edge states is established for the edge of these systems with the Dirac point locating at the bulk gap, and their QSH states are confirmed with topological invariant Z2 = 1. The films on BN substrate also maintain a nontrivial large-gap QSH effect, which harbors a Dirac cone lying within the band gap. These findings may shed new light in future design and fabrication of large-gap QSH insulators based on two-dimensional honeycomb lattices in spintronics.
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong, 250022, People's Republic of China.
authors.forename: Run-wu
authors.initials: RW
authors.lastname: Zhang
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong, 250022, People's Republic of China.
authors.forename: Chang-wen
authors.initials: CW
authors.lastname: Zhang
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong, 250022, People's Republic of China.
authors.forename: Wei-xiao
authors.initials: WX
authors.lastname: Ji
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong, 250022, People's Republic of China.|School of Physics, State Key laboratory of Crystal Materials, Shandong University, Jinan, Shandong, 250100, People's Republic of China.
authors.forename: Sheng-shi
authors.initials: SS
authors.lastname: Li
authors.affiliation: School of Physics, State Key laboratory of Crystal Materials, Shandong University, Jinan, Shandong, 250100, People's Republic of China.
authors.forename: Shi-shen
authors.initials: SS
authors.lastname: Yan
authors.affiliation: School of Physics, State Key laboratory of Crystal Materials, Shandong University, Jinan, Shandong, 250100, People's Republic of China.
authors.forename: Shu-jun
authors.initials: SJ
authors.lastname: Hu
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong, 250022, People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong, 250022, People's Republic of China.
authors.forename: Pei-ji
authors.initials: PJ
authors.lastname: Wang
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong, 250022, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Li