Overall performance of spin-valves using CoFe/Cu/CoFe as free FM layers

Summary form only given. Significant improvement of MR ratio can be realized in specular spin-valves (SVs) either by adding one noble metal layer used as spin-filter layer or by inserting nano-oxide layers both in the free and pinned FM layers. We have investigated the effect of using CoFe/Cu/CoFe as the free FM layer on the overall properties of SVs, such as, the change of sheet resistance (/spl Delta/R/sub s/), the MR ratio, and the interlayer coupling field (H/sub int/) etc. The structure of SVs studied was: Ta/NiFe/IrMn/CoFe(t/sub 1/)/Cu/CoFe/Cu/CoFe/Ta. We find that the MR ratio increases with increasing t/sub 1/ and is almost saturated when t/sub 1/, is larger than 1nm. These effects become more notable when the surface roughness at the interface is improved. This will be addressed in detail.