Double-injector source of spin polarized current with controllable polarization

We present low-temperature measurements of Co∕Al spin valves with a double-injector source of spin polarized current. Using an in-plane magnetic field, the injector electrodes were magnetized in opposite directions. The spin polarization of the injected current was controlled by changing the ratio of currents through the two electrodes and was continuously varied from zero up to the maximum spin polarization of Co. This result was verified by measuring the spin valve signal, using the detector electrode magnetized to align with one of the injectors. This source can be used for spintronic applications as well as in research on hybrid ferromagnet/superconductor structures.