Electrical detection of photoinduced spins both at room temperature and in remanence

We demonstrate a photodetector with ferromagnetic contacts which can electrically detect the polarization degree of incoming light using spin filtering of photoinduced spin-polarized electron currents. Our structure is a pin diode with a single GaAs quantum well as active region and a Fe/Tb multilayer on top of a MgO tunnel barrier as n-contact where the spin-polarized electron current is filtered. The photocurrent depends on the magnetization of the contacts and on the polarization of the injected light. We prove that even in remanence and at room temperature the degree of circular polarization of the incident light can be unambiguously determined by the photocurrent intensity. (C) 2008 American Institute of Physics.