Perpendicular spin valve behavior in a microstructured Co/Cu‐Cu oxide/Co trilayer

In this article we report a perpendicular spin valve behavior in a microstructured noncoupling magnetic trilayer system of Co/Cu‐Cu oxide/Co. The Co thin films having markedly different coercivity Hc were prepared with a vacuum evaporation with electron beam (Hc= 20–30 Oe) and rf sputtering (Hc= 90–260 Oe), which enables the selective switching of the magnetization in the base and counter Co layers. The film surface of the Cu was oxidized by the rf sputter etching, which results in the increase of the resistance for the perpendicular current and enables measurements of the perpendicular spin valve behavior at room temperature. The additional spacer layer of sputtered SiO2 with a contact hole of 5 μm diameter was fabricated with photolithographic method between the bottom Co and the intermediate Cu layer, which defined the current path perpendicular to the film plane. The measured magnetoresistance ratio was 0.85% (dR=7.6 mΩ, R=0.89 Ω) at room temperature.