MAGNETISM AND GIANT MAGNETOTRANSPORT PROPERTIES IN GRANULAR SOLIDS

Magnetic granular solids consist of nanometer-sized magnetic particles uniformly dispersed and embedded in an immiscible insulating or metal lic medium. They display a rich variety of magnetic properties and gia nt magneto-transport properties due to their unique nanostructure, whi ch can be usefully described by the metal volume fraction and the meta l particle diameter of granular solids. Fabrications and characterizat ions of granular solids, their enhanced magnetic properties, percolati on behavior, single-domain characteristics, superparamagnetic relaxati on, and superparamagnetism are reviewed. Giant magneto-transport prope rties, recently observed in granular solids, including giant magnetore sistance, extraordinary Hall resistivity, magneto-thermal conductivity , and Wiedemann-Franz law are discussed.