Abstract
Magnetoresistance(MR) effect has been observed for Fe/Ag granular alloys. 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 clusters by annealing the supersaturated fcc solid solution : it becomes largest after annealing at 570 K and decreases after annealing at higher temperatures. In the Fe/Ag granular alloys made by ion-cluster- beam (ICB) method, MR is largest at the as-deposited state and it monotonically decreases with annealing at higher temperatures. MR of the as-deposited state does not saturates even at a high field of 140 kOe. This feature is more marked in the sputter-deposited alloys than in the ICB-deposited ones. These results indicate that the MR effect is optimized in the ICB-deposited alloys, because nanoscale ferromagnetic Fe clusters have been formed in the as-deposited state in contrast to their formation by annealing in the sputter-deposited alloys.