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 o bserved 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 decease rho(0) - rho(H) in resistivity plotted versus the square of ma gnetization shows clearly two regimes: under low fields, it presents a linear variation independent of the temperature; under high fields (M /M(s) > 0.7), it deviates from it with an increasing slope. This behav iour is discussed in the framework of a recent model developed for gra nular materials.