Giant magnetoresistance study of granular Co-Fe/Ag thin films: correlation with magnetization

We have studied the giant magnetoresistance of evaporated Co65Fe35/Ag alloys and we have correlated the effect with magnetization. We have observed a maximum effect of 92% at 4.2 K under a field of 60 kOe. The room-temperature effect can be roughly evaluated to 35%. The absolute decrease rho (0)- rho (H) in resistivity plotted versus the square of magnetization shows clearly two regimes: under low fields, it presents a linear variation independent of the temperature; under high fields (M/Ms>0.7), it deviates from it with an increasing slope. This behaviour is discussed in the framework of a recent model developed for granular materials.