PHOTO-ASSISTED TUNNELING AT FERROMAGNET SEMICONDUCTOR INTERFACES

We have measured the polarization-dependent photoresponse of ferromagn et-insulator-(III-V) semiconductor thin film tunnel structures as a fu nction of wavelength. When the structures have no interfacial barrier, we find that the response agrees well with calculations of magneto-op tical transmission through the magnetic overlayer. However, when a tun nel barrier is present and excitation nearly resonant with the semicon ductor bandgap, we observe significant deviations from the magneto-opt ical effects. These deviations are attributed to spin-dependent electr on transmission from the III-V semiconductor acting as a spin-polarize d source of tunneling electrons.