Electrical Spin Injection from Out-of-Plane Magnetized FePt/MgO Tunneling Junction into GaAs at Room Temperature

We have succeeded in demonstrating zero-magnetic-field spin injection in metal–insulator–semiconductor (MIS) structure at room temperature using FePt/MgO/GaAs-based light-emitting diode heterojunction with out-of-plane magnetization. The spin polarization was investigated by spin-polarized electroluminescence (EL). The lower estimate injected at remanence was 1.5% and that injected at 1 T was reached up to 11.5%. The spin injection efficiency was estimated at least 29%. The bias dependence of the EL circular polarization showed that it decreases with increasing bias voltage for both at 1 T and at remanence.