Specular spin-valve films with an FeCo nano-oxide layer by ion-assisted oxidation

We compared the specular spin-valve films with an Fe ₅₀Co ₅₀ nano-oxide layer (NOL) and a Co ₉₀Fe ₁₀ NOL in a pinned layer, prepared by natural oxidation (NO) and ion-assisted oxidation (IAO). For the IAO, an Ar-ion beam was used for the energy-assist effect during the oxidation, resulting in thermally stable NOL formation. With small oxygen exposures during the oxidation for the Fe ₅₀Co ₅₀ NOL by IAO, good ferromagnetic coupling through the NOL and high specularity at the NOL interface were concurrently obtained. Moreover, twisted coupling through the NOL was observed for the Fe ₅₀Co ₅₀ NOL by IAO for higher oxygen exposures. On the other hand, the NO did not cause large magnetoresistance (MR) enhancement for either the Co ₉₀Fe ₁₀ or Fe ₅₀Co ₅₀ NOLs, and the Co ₉₀Fe ₁₀ NOL by IAO caused weak magnetic coupling through the NOL, resulting in a small MR ratio. The Fe ₅₀Co ₅₀ NOL for small oxygen exposures is a good candidate for a final specular spin-valve film head for 100-Giga-bit per square inch recording.