Probing the Topological Surface States through Magnetoresistance and Ultrafast Charge Carrier Dynamics in (Bi/Sb)2Te3

TL;DR

This study investigates the topological surface states in (Bi/Sb)2Te3 topological insulators through magnetoresistance and ultrafast spectroscopy, revealing their presence and charge carrier dynamics at low temperatures.

Contribution

It provides experimental evidence of topologically protected surface states using magnetoresistance and ultrafast spectroscopy in single-crystalline (Bi/Sb)2Te3.

Findings

Weak anti-localization indicates topological surface states.

Ultrafast spectroscopy reveals charge carrier dynamics related to surface states.

Surface states are confirmed at low temperatures through optical transitions.

Abstract

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.