title: A new kind of 2D topological insulators BiCN with a giant gap and its substrate effects.
abstract: Based on DFT calculation, we predict that BiCN, i.e., bilayer Bi films passivated with -CN group, is a novel 2D Bi-based material with highly thermodynamic stability, and demonstrate that it is also a new kind of 2D TI with a giant SOC gap (~1 eV) by direct calculation of the topological invariant Z2 and obvious exhibition of the helical edge states. Monolayer h-BN and MoS2 are identified as good candidate substrates for supporting the nontrivial topological insulating phase of the 2D TI films, since the two substrates can stabilize and weakly interact with BiCN via van der Waals interaction and thus hardly affect the electronic properties, especially the band topology. The topological properties are robust against the strain and electric field. This may provide a promising platform for realization of novel topological phases.
authors.affiliation: School of Physics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Botao
authors.initials: B
authors.lastname: Fu
authors.affiliation: School of Physics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Ge
authors.affiliation: School of Physics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Wenyong
authors.initials: W
authors.lastname: Su
authors.affiliation: School of Physics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.affiliation: School of Physics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Cheng-Cheng
authors.initials: CC
authors.lastname: Liu