High speed pulsed electrical spin injection in spin-light emitting diode

We demonstrate high speed pulsed electrical spin injection from a CoFeB/MgO spin injector into a AlGaAs/GaAs semiconductor light emitting diode. Under pulsed electrical excitation, time-resolved electroluminescence on nanosecond time scale exhibits a plateau of circular polarization degree as high as 15% under a 0.8 T magnetic field. It follows an initial decay that could be due to electron spin-relaxation process in the quantum well embedded in the intrinsic region of the diode. The temporal buildup of the electronic spin polarization degree in the quantum well is much faster than the rise time of electroluminescence intensity.