Dipolar interaction and magnetic ordering in granular metallic materials.

Altbir D., Vargas P., Castro J. D. E., Raff U.

Univ Santiago Chile Dept Fis Casilla 307 Santiago 2 Chile
Max Planck Inst Festkorperforsch D-70569 Stuttgart Germany
Univ Fed Fluminense Inst Fis Br-24210340 Niteroi Rj Brazil

The coupling between magnetic clusters in granular metals is investigated assuming a classical dipolar interaction to couple the clusters. It is shown that in general the dipolar interaction energy is well described by replacing the clusters by an effective magnetic moment located at the center of mass of the cluster. The magnetization and reduced magneto resistance of these systems are described as a function of an external magnetic field for a variety of cluster distributions. An experimental design that yields a system with high reduced magnetoresistance is suggested.

Physical Review B, 57 13604-13609, 1998.

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