Unveiling trivial and topological 1D states in Bi monolayers

Anisotropy and non-trivial topology are both highly sought properties in 2D quantum materials, as both can lead to 1D electronic states of very different nature, spatial localization, and response to interactions. Bi is a good candidate for hosting such states, since particular Bi monolayer allotropes can adopt highly anisotropic structures as that of black phosphorous (α-Bismuthene), and some are predicted to host non-trivial electronic states at their edge boundaries (e.g. α- and β-Bismuthene). Here we aim at demonstrating the emergence of coexisting trivial (bulk) and topological (edge) 1D states in a new Bi monolayer allotrope consisting of half α-Bismuthene bilayer, and to explore their electronic interplay.