Oscillatory spin-filtering due to gate control of spin-dependent interface conductance

Using the Landauer-Büttiker formalism, we study ballistic transport properties of an interface between a ferromagnetic metal and a mesoscopic two-dimensional electron system in a III-V semiconductor. We show that in a Sharvin point contact spin-filtering occurs due to band structure mismatch. Theory predicts a pronounced effect for Fe on InAs which can be controlled via a gate electrode.