Helicity dependent photocurrent in electrically gated (Bi_1-x Sb _x )₂Te₃ thin films.

ABSTRACT: Circularly polarized photons are known to generate a directional helicity-dependent photocurrent in three-dimensional topological insulators at room temperature. Surprisingly, the phenomenon is readily observed at photon energies that excite electrons to states far above the spin-momentum locked Dirac cone and the underlying mechanism for the helicity-dependent photocurrent is still not understood. Here we show a comprehensive study of the helicity-dependent photocurrent in (Bi_1-x Sb _x )₂Te₃ thin films as a function of the incidence angle of the optical excitation, its wavelength and the gate-tuned chemical potential. Our observations allow us to unambiguously identify the circular photo-galvanic effect as the dominant mechanism for the helicity-

SUBMITTER: Pan Y 

PROVIDER: S-EPMC5648839 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature