CHARACTERISTIC HIGH-FIELD DEPENDENCE OF MAGNETORESISTANCE IN FE AG GRANULAR THIN-FILMS FABRICATED BY SPUTTERING AND ANNEALING/

Magnetoresistance (MR) have been measured at 4.2 K in magnetic fields up to 140 kOe for Fe/Ag granular films produced by sputtering and heat treatment. In a Ag-rich specimen, the MR ratio is larger than 25% eve n in the as-deposited state, whereas it is suppressed with increasing Fe content. The MR ratio becomes about 55% in the 14 at. % Fe specimen annealed at 573 K for 10 min. Based upon the giant MR (GMR) models of granular materials, these results indicate the importance of Fe parti cle size and Fe/Ag interface roughness in achieving GMR.