Anomalous circular photogalvanic effect of the spin-polarized two-dimensional electron gas in Mg_0.2Zn_0.8O/ZnO heterostructures at room temperature

A spin-related photocurrent with swirly distribution and anomalous dependence of the total spin-related photocurrent on the incident angle were observed on spin-polarized two-dimensional gas in a Mg_0.2Zn _0.8O/ZnO heterostructure under illumination of circular polarized light at room temperature. The ferromagnetic two-dimensional Rashba model was adopted to interpret the results. It is demonstrated that a radial spin current induced by the gradient of the spin-polarized electron density is the origin of the anomalousness. This spin current only exists in spin polarized systems.