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

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.