Strain & Topological Interface States

In this paper we show how strain turns the newly discovered topological insulators into normal insulators and disclose a path towards strained-based topological electronics. We calculated the effect of strain on the electronic band structure of the bismuth dichalcogenide family, which hosts several of the best-known topological insulators, and found that strain changes the band gap of the materials and may suppress their topological conducting surface states. We derived a universal phase diagram for these compounds, that describes the strain at which the transition to the normal insulating o metallic state occurs. Base on our findings, we propose an electronic device with switchable topological conducting states. The conducting states are formed at the interface of two different bismuth dichalcogenides, have a precise value of their spin and are topological protected, i.e.: immune to defects in the samples, as well as safe from ambient impurities, as opposed to topological states at surfaces. Additionally, these states can be switched on or off, while preserving their topological nature.