Electric-field-induced spin injection enhancement.

ABSTRACT

The spin diffusion process can be modified by the electric field in a semiconductor channel. The electric field generated by the bias current improves the spin injection efficiency as well as the spin diffusion length at a ferromagnet-semiconductor hybrid system. Spin-polarized electrons from the ferromagnetic electrode were electrically investigated in an inverted heterostructure with an In0.53Ga0.47As active layer. Using local and non-local spin valve geometries, the interfacial spin polarizations with and without an electric field are extracted from the magnitude of spin transport signals. The interfacial spin polarization is increased from 3.2% to 7.0% with a current of 1 mA at T = 20 K. When the electric field assists the spin injection at the junction, the interfacial spin polarization remains 7% at the temperature ranged from 20 K to 200 K. Temperature dependence of the injected polarization shows that the electric field can compensate the thermal smearing of injection efficiency even at higher temperature.