Electrical spin injection in ferromagnetic/nonmagnetic semiconductor heterostructures

Magneto-electroluminescence properties of ferromagnetic/nonmagnetic semiconductor pn junction light emitting diodes (LEDs) are presented. A ferromagnetic p-type (Ga,Mn)As layer is grown on i-(In,Ga)As quantum well (QW)/n-GaAs so that the degree of spin polarization of holes injected from (Ga,Mn)As into GaAs can be probed by analyzing the polarization of light emitted from the LED structures. The EL polarization as a function of magnetic field exhibits clear hysteresis below the ferromagnetic transition temperature of (Ga,Mn)As, which is the evidence that spin-polarized electrical current is injected into nonmagnetic semiconductor.