Tuning the interaction between the bulk and edge states of topological
materials is a powerful tool for manipulating edge transport behavior, opening
up exciting opportunities for novel electronic and spintronic applications.
This approach is particularly suited to topological crystalline insulators
(TCI), a class of topologically nontrivial compounds that are endowed with
multiple degrees of topological protection. In this study, we investigate how
bulk-edge interactions can influence the edge transport in planar bismuthene, a
TCI with metallic edge states protected by in-plane mirror symmetry, using
first principles calculations and symmetrized Wannier tight-binding models. By
exploring the impact of various perturbation effects, such as device size,
substrate potentials, and applied transverse electric field, we examine the
evolution of the electronic structure and edge transport in planar bismuthene.
Our findings demonstrate that the TCI states of planar bismuthene can be
engineered to exhibit either a gapped or conducting unconventional helical spin
texture via a combination of substrate and electric field effects. Furthermore,
under strong electric fields, the edge states can be stabilized through a
delicate control of the bulk-edge interactions. These results open up new
directions for discovering novel spin transport patterns in topological
materials and provide critical insights for the fabrication of topological
spintronic devices.Comment: 23 pages, 8 figure