Influence of the interactions on the magnetotransport properties of Fe-Ag granular thin films.

: Fe(x)Ag(100-x) granular thin films, 25 < or = x < or = 40, have been prepared by DC-Magnetron sputtering deposition. These samples are composed of small Fe nanoparticles (2.5-3 nm) embedded in an Ag matrix, and their size remains nearly constant with increasing Fe content. A crossover in the collective magnetic behaviour of the samples near x = 35, had been previously reported for these samples. In this article, we show that the transport and magnetotransport properties are clearly correlated with these magnetic behaviours, and that the resistivity, the magnetoresistance and the Hall resistivity depend on the nature of the most relevant interactions, dipolar or direct exchange, as a function of the thermal evolution and the Fe content.