Abstract

In this study, we generate spin polarised electrons in GaAs near an epitaxial Fe/GaAs interface using optical spin orientation. By applying high forward bias, we remove or invert the Schottky barrier. A spin filtering current was obtained as a function of bias for opposite magnetic fields. The results reveal a clear spin filtering in the absence of a tunnelling barrier and suggest a successful experimental demonstration of ballistic spin transport across an epitaxial Fe/GaAs interface. Using a simple transport model based on a transfer matrix approach within an effective mass approximation, we semi-quantitatively obtain the polarisation of the interfacial density of states by fitting our experimental data. By comparing with the theoretical results based on a tight-binding approach by Honda et al.[1], our experimental results suggest the interface is a mixture of Fe-As and Fe-Ga terminated structure.