Stray field interaction in PtCo/SiO2/NiFe multilayer thin film structures

Integral high coercivity sputtered PtCo thin magnetic films are used to bias magnetoresistive sensors. The devices utilize a three-layer structure of NiFe and PtCo thin films separated by an SiO₂ spacer layer. The hard- and easy-axis coercivities of the NiFe layer are shown to be strongly dependent on the spacer thickness for values of thickness below about 200 nm. The stray field interaction between the layers is modeled by representing magnetic inhomogeneities in the PtCo layer as a rectangular array of regions with randomly aligned but uniform magnetization. Scaling adjustments to only two parameters, the magnitude of the magnetization inhomogeneity and the boundary spacing, gives a good fit to the experimental results.