title: First-principles prediction of a giant-gap quantum spin Hall insulator in Pb thin film.
abstract: The quantum spin Hall (QSH) effect is promising for achieving dissipationless transport devices due to the robust gapless states inside the insulating bulk gap. However, QSH insulators currently suffer from requiring extremely high vacuums or low temperatures. Here, using first-principles calculations, we predict cyanogen-decorated plumbene (PbCN) to be a new QSH phase, with a large gap of 0.92 eV, that is robust and tunable under external strain. The band topology mainly stems from s-pxyband inversion related to the lattice symmetry, while the strong spin-orbit coupling (SOC) of the Pb atoms only opens a large gap. When halogen atoms are incorporated into PbCN, the resulting inversion-asymmetric PbFx(CN)1-xcan host the QSH effect, accompanied by the presence of a sizable Rashba spin splitting at the top of the valence band. Furthermore, the Te(111)-terminated BaTe surface is proposed to be an ideal substrate for experimental realization of these monolayers, without destroying their nontrivial topology. These findings provide an ideal platform to enrich topological quantum phenomena and expand the potential applications in high-temperature spintronics.
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China. ss_zhangchw@ujn.edu.cn.
authors.forename: Hui
authors.identifier: http://orcid.org/0000-0003-1151-5336
authors.initials: H
authors.lastname: Zhao
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China. ss_zhangchw@ujn.edu.cn.
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. ss_zhangchw@ujn.edu.cn.
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. ss_zhangchw@ujn.edu.cn.
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. ss_zhangchw@ujn.edu.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.affiliation: School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China. ss_zhangchw@ujn.edu.cn.
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. ss_zhangchw@ujn.edu.cn.
authors.forename: Run-Wu
authors.initials: RW
authors.lastname: Zhang