Effect of seed layer on the magnetoresistance characteristics in a-CoNbZr-based spin valves

We have investigated an amorphous-based spin valve structure of NiO(40 nm)/Co(2)/Cu(t)/Co(1.2)/CoNbZr(20) for the application of magnetic random access memory. The spin valves were prepared on Si(100) by sputtering, and characterized by XRD, VSM, AFM/MFM, and 4-point probe. To improve GMR characteristics by controlling the interfacial structures of the Co/Cu/Co trilayer, we employed NiFe as a seed layer for NiO and achieved a GMR ratio of 10.7%. The spin valves with the seed layer exhibited lower ferromagnetic coupling between the pinned and free layers, lower pinning fields, and higher coercivities of the pinned layer than the spin valves without a seed layer. These phenomena were discussed mainly in terms of interfacial microstructural change as well as Neel's orange peel model.