Creating spin currents with a ferromagnetically-gated silicon inversion layer

Novel spin transport behavior is shown to result from replacing the metal gate with a ferromagnet in a silicon field-effect transistor. The coupling of inversion-layer electrons to the ferromagnetic gate results in spin-dependent transport in the device; an ultra-thin gate oxide is required to optimize the effect. The interplay between the drift current (due to a source-drain bias) and the diffusion current (due to electron leakage into the biased gate) allows for a rich variety of spin-dependence in the current that flows through such a device. In the regime of low source-drain bias, both 100 percent spin-polarized electrical currents and pure spin currents are possible.