Robustness of helical edge states in topological insulators

Topological insulators (TIs) are materials having an energy band gap in the bulk and conducting helical electronic states on the surface. The helical states are protected by time-reversal symmetry and thus are expected to be robust against static disorder scattering. In this work we report an atomistic first principles analysis of disorder scattering in two-probe transport junctions made of three-dimensional TI material Bi2Se3. The robustness of the device against disorder scattering is determined quantitatively. Examining many different scattering configurations, a general trend emerges on how strong is the perturbing potential and how it is spatially distributed so that it can derail the helical states on the Bi2Se3 surfaces.