Large magnetoresistance ratio of 10% by Fe ₅₀ Co ₅₀ layers for current-confined-path current-perpendicular-to-plane giant magnetoresistance spin-valve films

We have realized a large magnetoresistance (MR) ratio of 10.2% by current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) spin-valve films having current-confined-path (CCP) structure formed by AlCu-NOL (nano-oxide-layer). CPP-GMR with conventional Co90 Fe10 pinned and free layers showed an MR ratio and a ΔRA (the change of resistance area product) were 4% and 20 mΩ μ m2, respectively, at a small RA (resistance area product) of 500 mΩ μ m2. By replacing the Co90 Fe10 layers by Fe50 Co50 layers both for pinned and free layers, we have successfully realized a MR ratio and a ΔRA of 7.5% and 37.5 mΩ μ m2, respectively, at a small RA of 500 mΩ μ m2. Moreover, a large MR ratio of 10.2% and a large ΔRA of 418 mΩ μ m2 were realized at a relatively large RA of 4100 mΩ μ m2. This large MR ratio by using Fe50 Co50 layers was due to a larger spin-dependent interface scattering factor γ of 0.72 for the interface between Fe50 Co50 and Cu, which was improved from a γ of 0.62 for the interface between Co90 Fe10 and Cu.