MAGNETORESISTANCE IN FE AG GRANULAR ALLOYS PRODUCED BY ION-CLUSTER-BEAM AND SPUTTERING/

Magnetoresistance(MR) effect has been observed for Fe/Ag granular allo ys. In the Fe-Ag alloys made by sputtering, MR is rather small at the as-deposited state. The MR effect is enhanced as Fe atoms form cluster s by annealing the supersaturated fcc solid solution: it becomes large st after annealing at 570 K and decreases after annealing at higher te mperatures. In the Fe/Ag granular alloys made by ion-cluster- beam (IC B) method, MR is largest at the as-deposited state and it monotonicall y decreases with annealing at higher temperatures. MR of the as-deposi ted state does not saturates even at a high field of 140 kOe. This fea ture is more marked in the sputter-deposited alloys than in the ICB-de posited ones. These results indicate that the MR effect is optimized i n the ICB-deposited alloys, because nanoscale ferromagnetic Fe cluster s have been for-med in the as-deposited state in contrast to their for mation by annealing in the sputter-deposited alloys.