Electrical spin injection in a ferromagnet/tunnel barrier/semiconductor heterostructure

We demonstrate experimentally the electrical electron spin injection from a ferromagnetic metal/tunnel barrier contact into a III–V semiconductor light emitting diode (LED). The injected electrons have in-plane spin orientation. By applying a relatively small oblique external magnetic field this spin orientation within the semiconductor can be manipulated to have a nonzero out-of-plane component. By measuring the resulting circular polarization of the emitted light, we observe injected spin polarization in excess of 9% at 80 K in a ${\mathrm{CoFe/AlO}}_x\mathrm{/(}\mathrm{Al,Ga})\mathrm{As/GaAs}$ surface-emitting spin-LED.