Analytical model of spin filtering effect and its experimental verification in a forward-biased iron-metal–Al

An analytical model for the spin filtering transport in a ferromagnetic-metal–Al2O3–n-type semiconductor tunneling structure has been developed, and demonstrated that the ratio of the helicity-modulated photo-response to the chopped one is proportional to the sum of the relative asymmetry in conductance of two opposite spin-polarized tunneling channels and the MCD effect of the ferromagnetic metal film. The performed measurement in an iron-metal/Al2O3/n-type GaAs tunneling structure under the optical spin orientation has verified that all the aspects of the experimental results are very well in accordance with our model in the regime of the spin filtering. After the MCD effect of the iron film is calibrated by an independent measurement, the physical quantity of Δ Gt/Gt(Δ Gt=G$^\uparrow$t-G$^\downarrow$t is the difference of the conductance between two opposite spin tunneling channels, Gt=(G$^\uparrow$t+G$^\downarrow$t)/2 the averaged tunneling conductance), which concerns us most, can be determined quantitatively with a high sensitivity in the framework of our analytical model