Crossover of electron transmission mechanism and spin filtering effect at Fe/GaAs(001) interfaces

A clear correlation between the spin filtering effect of optically pumped spin-polarized electrons at Fe/GaAs(001) Schottky interfaces and its electron transmission mechanism is reported. Current-voltage (I-V) characteristics of the Schottky diode demonstrate tunneling and thermionic emission transmission processes in the low and high bias voltage regions, respectively. A spin filtering current contribution, on the other hand, exhibits a significant peak at a particular bias voltage while spin selectivity shows a shoulder at the same bias voltage. The bias voltage where the features occur corresponds well to the crossover regime of the electron transmission mechanisms. The spin selectivity also shows a field dependence similar to the magnetization curve, assuring that the spin selectivity has its origin in the spin filtering effect. (c) 2008 American Institute of Physics.