title: Two-dimensional Topological Crystalline Insulator Phase in Sb/Bi Planar Honeycomb with Tunable Dirac Gap.
abstract: We predict planar Sb/Bi honeycomb to harbor a two-dimensional (2D) topological crystalline insulator (TCI) phase based on first-principles computations. Although buckled Sb and Bi honeycombs support 2D topological insulator (TI) phases, their structure becomes planar under tensile strain. The planar Sb/Bi honeycomb structure restores the mirror symmetry, and is shown to exhibit non-zero mirror Chern numbers, indicating that the system can host topologically protected edge states. Our computations show that the electronic spectrum of a planar Sb/Bi nanoribbon with armchair or zigzag edges contains two Dirac cones within the band gap and an even number of edge bands crossing the Fermi level. Lattice constant of the planar Sb honeycomb is found to nearly match that of hexagonal-BN. The Sb nanoribbon on hexagonal-BN exhibits gapped edge states, which we show to be tunable by an out-of-the-plane electric field, providing controllable gating of edge state important for device applications.
authors.affiliation: Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: Chia-Hsiu
authors.initials: CH
authors.lastname: Hsu
authors.affiliation: Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: Zhi-Quan
authors.initials: ZQ
authors.lastname: Huang
authors.affiliation: Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: Christian P
authors.initials: CP
authors.lastname: Crisostomo
authors.affiliation: Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: Liang-Zi
authors.initials: LZ
authors.lastname: Yao
authors.affiliation: Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: Feng-Chuan
authors.initials: FC
authors.lastname: Chuang
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546.|Department of Physics, National University of Singapore, Singapore 117542.
authors.forename: Yu-Tzu
authors.initials: YT
authors.lastname: Liu
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546.|Department of Physics, National University of Singapore, Singapore 117542.|Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: Baokai
authors.initials: B
authors.lastname: Wang
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546.|Department of Physics, National University of Singapore, Singapore 117542.
authors.forename: Chuang-Han
authors.initials: CH
authors.lastname: Hsu
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546.|Department of Physics, National University of Singapore, Singapore 117542.
authors.forename: Chi-Cheng
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546.|Department of Physics, National University of Singapore, Singapore 117542.
authors.forename: Hsin
authors.initials: H
authors.lastname: Lin
authors.affiliation: Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: Arun
authors.initials: A
authors.lastname: Bansil