Photon helicity driven surface photocurrent in CuSe films

Abstract

We report excitation of the spin-polarized currents in CuSe nanocrystalline films and demonstrate that the inversion of the excitation photon helicity reverses the direction of the photocurrent propagating perpendicular to the plane of incidence. By performing measurements of the photocurrent propagating both along and perpendicular to the plane of incidence, we show that the observed spin-polarized currents originate from the circular surface photogalvanic effect (C-SPGE). In contrast to the conventional circular photogalvanic effect, which is associated with spin–orbit interaction and can be observed in gyrotropic media, the C-SPGE originates from the scattering of the spin-polarized charge carriers on the surface. We demonstrate that in CuSe films, the C-SPGE gives rise to the photon helicity sensitive photoresponse, making this material attractive for optoelectronics and spintronics applications.