Temperature-dependent evolution of topological surface states

Abstract

Topological insulators with their inherent surface states are highly promising quantum materials. This article reports the evolution of the topological surface states by low-temperature transport measurements through magnetoresistance and the femtosecond transient reflectance ultrafast spectroscopy (TRUS) on single-crystalline topological insulators, Bi2Te3 and Sb2Te3. The weak anti-localization (WAL) effect was observed in the magnetoresistance measurement, showing the presence of topological surface states at low temperatures. The TRUS at different temperatures, varying from room temperature (300 K) to a low temperature of 5 K, was also performed to observe the behaviour of the charge carrier dynamics, and interestingly, the evolution of the topological surface states have been observed. The coherent optical and acoustic phonons have been evaluated with respect to the temperature variation. In addition, the various transitions are also modeled with the help of band structures.