CPP-GMR enhancement in spin valves using a thin Ru layer

Current perpendicular to plane giant magnetoresistance (CPP-GMR) of single spin valves with two kinds free layers has been investigated. One is a single ferromagnetic layer (Conventional structure) and the other is a ferromagnetic layer with thin Ru cap layer (Ru cap structure). Both structure had increasing resistance and resistance changes with decreasing element size. The CPP-GMR ratio for a Ru cap structure was enhanced from 0.70 to 4.3% at room temperature. We think the MR enhancement is caused by the spin dependent scattering due to strong reflection of majority spins at the Co90Fe10/Ru interface.