FLEET Internal Seminar – Models for electron transport in the two-dimensional allotropes of bismuth

Jackson Smith, RMIT

Abstract: In two-dimensional (2D) materials with honeycomb lattices, such as graphene, spin-orbit coupling is predicted to cause the existence of edge states [1].  The 2D allotropes of bismuth are no exception to this prediction. Although bulk bismuth has been shown to be a topologically trivial semi-metal [2], the 2D allotropes of bismuth show properties that are topologically non-trivial [3, 4, 5].  In this work, we calculate the band structure of the 2D allotropes of bismuth using density-functional theory (DFT) and then develop tight-binding models of these materials by fitting their energy bands with a basis of maximally-localised Wannier functions.  We do this for bismuthene and the (111) and (110) bismuth bilayers.  Accurate TB models for the 2D allotropes of bismuth are needed to simulate electron transport, which we do for bismuth with a non-equilibrium Green’s function method.

1. Kane and Mele, PRL 95, 146802 (2005).
2. Fu and Kane, PRB 76, 045302 (2007).
3. Murakami, PRL 97, 236805 (2006).
4. Bieniek et al., J. Phys.: Condens. Matter 29 155501 (2017).
5. Reis et al., Science 357, 287–290 (2017).