  Topological insulators with their topological protected surface states are
highly promising quantum materials. In this article the micro-flakes of
single-crystalline topological insulators Bi2Te3 and Sb2Te3 are explored
through physical parameter measurement at low temperatures and thereby the
charge carrier dynamics are investigated at 5K to study the various optical
transitions related to these surface states. The magnetoresistance is
experimentally investigated at temperatures of 5K and 100K for a field range of
1Tesla. The occurrence of the weak anti-localization effect predicts the
presence of topologically protected surface states in the systems. Further, the
ultrafast femtosecond transient reflectance spectroscopy is performed at
different temperatures, varying from a room temperature (300K) to a low
temperature of 5K, to find the TSS related transitions at low temperatures.

Materials Science