Proximity magnetoresistance in Ag70Fe30 and Ag74Fe26 cosputtered granular films

Granular films of composition Ag70Fe30 and Ag74Fe26 were prepared by dc plasma sputtering deposition in Ar atmosphere on Si substrates. Magnetization and magnetoresistance were measured between 2 K and 270 K. Both films exhibit a negative magnetoresistance (MR). The MR vs. reduced magnetisation curves are characterised by a box-like behavior, as already observed in magnetic systems with competing interactions. A standard analysis indicates that in both systems individual Fe nanoparticles are magnetically correlated over large distances