Microstructure and magnetic properties of Mn–Ir based specular spin valve multilayer with nano oxide layer

Si/Ta/Ni–Fe/Mn–Ir/Co–Fe/NOL/Co–Fe/Cu/Co–Fe/Ta bottom specular spin valves were prepared by dc magnetron sputtering method. Under optimal oxidation conditions, the magnetoresistance ratio (MR ratio) and the Hex (exchange bias field) increased from 7.8% and 247 Oe without nano oxide layer (NOL) to 10.3% and 320 Oe with NOL, respectively. And the Hin (interlayer coupling field) decreased from 35 to 19 Oe. These results indicate that NOL in the Co–Fe pinned layer improves the magnetic and electrical properties of spin valve. The NOL is formed discontinuously and this thickness range is about 0.5–2 nm. The chemical analysis shows that Fe-oxide is formed preferentially in the NOL.