"Absence of strong localization at low conductivity in the topological surface state of low-disorder Sb2 Te3"

Ilan T. Rosen,: Indra Yudhistira, Girish Sharma, Maryam Salehi, M. A. Kastner, Seongshik Oh, Shaffique Adam, and David Goldhaber-Gordon; Physical Review B, 05/02/19.

Additional Authors: Indra Yudhistira, Girish Sharma, Maryam Salehi, M. A. Kastner, Seongshik Oh, Shaffique Adam, and David Goldhaber-Gordon

Abstract:

We present low-temperature transport measurements of a gate-tunable thin-film topological insulator system that features high mobility and low carrier density. Upon gate tuning to a regime around the charge neutrality point, we infer an absence of strong localization even at conductivities well below e2/h, where two-dimensional electron systems should conventionally scale to an insulating state. Oddly, in this regime the localization coherence peak lacks conventional temperature broadening, though its tails do change dramatically with temperature. Using a model with electron-impurity scattering, we extract values for the disorder potential and the hybridization of the top and bottom surface states.