MAGNETORESISTANCE IN GRANULAR-MATERIALS AND SIZE EFFECTS

Considering dipolar interactions between magnetic grains, the effect o f cluster size distributions in the magnetoresistance of granular meta llic systems is analyzed. In particular, the reduced magnetoresistance and magnetization are studied for different systems, and it is shown that when a broad grain size distribution is considered, strong effect s are observed. However, the dipole-dipole short range correlation at zero field does not change, when a cluster size distribution is consid ered. Therefore the reduced magnetoresistance value at zero field is n ot affected.