Large and robust electrical spin injection into GaAs at zero magnetic   field using an ultrathin CoFeB/MgO injector
  We demonstrate a large electrical spin injection into GaAs at zero magnetic field thanks to an ultrathin perpendicularly magnetized CoFeB contact of a few atomic planes (1.2 nm). The spin-polarization of electrons injected into GaAs was examined by the circular polarization of electroluminescence from a Spin Light Emitting Diode with embedded InGaAs/GaAs quantum wells. The electroluminescence polarization as a function of the magnetic field closely traces the out-of-plane magnetization of the CoFeB/MgO injector. A circular polarization degree of the emitted light as large as 20% at 25 K is achieved at zero magnetic field. Moreover the electroluminescence circular polarization is still about 8% at room temperature. 
S. Liang, T.T. Zhang, P. Barate, J. Frougier, M. Vidal, P. Renucci, B.   Xu, H. Jaffr\`es, J.M. George, X.Devaux, M. Hehn, X...
cond-mat.mtrl-sci