Numerical calculation model for spin-dependent transport of photoexcited electrons across Fe/GaAs(0 0 1) interfaces

Spin-dependent transport of photogenerated electrons across Fe/GaAs(0 0 1) interfaces is calculated using a one-dimensional electron transport model. Creation of spin-polarized electrons by photoexcitation in this model is defined by the band structure of GaAs along the [0 0 1] direction and the optical selection rules. The tunnel probability across the interface is obtained from Chang's model and first principles calculations are employed to calculate the spin polarization of Fe for electrons propagating along the [0 0 1] direction. By combining the above ingredients, the spin-filtering current, ISF, was calculated for different parameter values, including Schottky barrier height and photon energy. The model is used to fit with experimental results of the photoexcitation technique, yielding qualitative agreement especially for the observed sign switching of the spin-filtering current.