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 Bi2Te3 films is investigated. It is revealed that the helicity-dependent photoconductivity current on the left edge of the Bi2Te3 film shows an opposite sign with that on the right edge. In addition, the helicity-dependent photoconductivity current increases linearly with the applied longitudinal electric field, and it reverses the sign with the reversal of the electric field. As the thickness of the Bi2Te3 film increases, the helicity-dependent photoconductivity current also increases. Theoretical analysis suggests 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.