Helicity-dependent photoconductance of the edge states in the topological insulator Bi₂Te₃

Abstract

The helicity-dependent photoconductance of the edge states in three-dimensional topological insulator Bi$_2$Te$_3$ films was investigated. It was revealed that the helicity-dependent photoconductivity current on the left edge of the Bi$_2$Te$_3$ film showed an opposite sign with that on the right edge. Besides, the helicity-dependent photoconductivity current increased linearly with the applied longitudinal electric field, and it reversed the sign as the reversal of the electric field. As the thickness of the Bi$_2$Te$_3$ film increased, the helicity-dependent photoconductivity current also increased. Theoretical analysis suggested that the helicity-dependent photo-conductivity current may come from the intrinsic spin orbit coupling (SOC) or the SOC introduced by the chiral impurities or defects.