Graphene-Bi (111) interface: atomic structure and electronic properties

Interfacial interactions are widely used to engineer desired electronic properties. In this context, the interface between graphene and nanostructured bismuth is especially interesting since both the materials
exhibit unique properties associated respectively with the Dirac cones and quantum spin-Hall states along the edges and hinges. In this work, using first-principles calculations, we study the interfacial interaction between graphene and Bi (111) surfaces. Since the actual structure of graphene on Bi (111) can be incommensurate, we investigated a large number of crystal approximants to the incommensurate interface and found the most stable one. Despite hybridization between graphene and substrate orbitals, the graphene-derived Dirac cones are preserved, although shifted with respect to the Fermi level due to the n-doping of graphene. We also find that a small gap opens up at the original Dirac points in these cones due to interface–induced spin–orbit coupling within graphene. At the same time, the bands near the gamma point are mostly Bi-derived and resemble the corresponding surface states in pure Bi. Using the obtained results, we discuss possible applications of graphene/Bi interfaces in future electronic devices.