Electron–phonon interactions at the topological edge states in single bilayer Bi(111)

Abstract

An intriguing feature of two-dimensional topological insulators is the topologically protected electronic edge state, which allows one-way carrier transport without backscattering. Although this feature has strong potential applications in lossless electronics, the ideal behavior of the edge states may be fragile due to electron–phonon (e–ph) interactions at room temperatures. Using density functional perturbation theory calculations for single bilayer Bi(111) as a prototypical 2D topological insulator, we show that e–ph scattering can be a significant source of backscattering at the topological edge states. We also show that e–ph interactions strongly correlate to the dispersions of the electronic edge states. In particular, the e–ph interactions increase significantly with temperature and are much stronger at the nonlinearly dispersed edge states of native edges compared to the linearly dispersed edge states of passivated edges, causing a significant energy dissipation in the temperature range of 200–400 K. Overall, we argue that the e–ph interactions can be a crucial factor at finite temperatures in controlling the electronic transport at the topologically protected edge states.