Optical Detection of Hot-Electron Spin Injection into GaAs from a Magnetic Tunnel Transistor Source

Injection of spin-polarized hot-electron current from a magnetic tunnel transistor into GaAs is demonstrated by the observation of polarized light emission from a GaAs/In_0.2Ga_0.8As multiple quantum well light-emitting diode. Electroluminescence from the quantum wells shows a polarization of ∼10% after subtraction of a linear background polarization. The polarization shows a strong dependence on the bias voltage across the diode, which may originate from changes in the electron spin relaxation rate in the quantum wells under varying bias conditions.