Multiple Extraction Spin Valves for Spintronic Circuits

The application of an electrical forward bias across a ferromagnet/semiconductor Schottky barrier can result in a non-equilibrium spin accumulation in the semiconductor. This mechanism is referred to as spin extraction. Like spin injection, spin extraction can also serve to generate the electron spin polarization, which is necessary for the operation of a local spin valve, i.e., a magnetoresistance device consisting of a ferromagnetic/non-magnetic/ferromagnetic hybrid structure, which exhibits an electrical resistance that depends on the relative orientation of the magnetizations of the two ferromagnetic electrodes. In such a spin extraction spin valve (SESV), a spin-polarized drift current is generated in a non-magnetic channel by spin extraction at a ferromagnetic electrode. The spin polarization influences the output current through a subsequent ferromagnetic electrode. We show how spin valve devices relying on multiple spin extraction events can be used for magneto-logic gate operation. Furthermore, we investigate the potential use of these structures as sources of highly spin-polarized drift currents.