THz radiation induced spin polarized currents in low dimensional semiconductor structures

In this work spin polarized currents were observed and studied in various low dimensional semiconductor systems under excitation with THz radiation. The measurements demonstrate that the microscopic origin of the photocurrents is the asymmetric spin-dependent scattering, which results in a spatial separation of electrons with opposite spins. During the spin separation a spin current flows, which is transformed into a net electric current by the application of an external magnetic field. This effect, known as the MPGE, was observed in different types of low dimensional GaAs structures and DMS (CdMn)Te QWs. Besides the fundamental question on the origin of the spin current formation, the variation of the inversion asymmetry in low dimensional systems, which is of particular interest for spintronics related research, was studied. To achieve this goal, spin polarized currents have been utilized as an experimental access to the inversion asymmetry. (orig.)