Remanent electrical spin injection from Fe into AlGaAs/GaAs light emitting diodes

We compare surface and edge emission electroluminescence of spin-polarized light emitting diodes with Fe contacts. The edge emission geometry permits transduction of the spin state variable between the electron spin and optical polarization utilizing the in-plane remanent magnetization and low coercive fields of the metal contacts. The spin injection efficiencies are similar for electron spins oriented normal to the surface plane and in plane. The lower circular polarization consistently observed in edge emission at low magnetic fields is attributed to a partial out-of-plane orientation of the heavy hole angular momentum which persists even in wide quantum wells. (c) 2006 American Institute of Physics.