A phenomenological model of percolating magnetic nanostructures

Transport and magnetotransport properties were analysed systematically in p ercolating magnetic nanostructures such as Ni-rich NiFe-SiO2 and Fe-SiO2 fi lms. These granular magnetic films exhibit giant Hall effect. We identified features which are common and unique to these systems. Among the features are the correlation between a - log(T)-like temperature dependent resistivi ty and a particle size distribution having a large fraction of small nanome ter sized particles, and the power law dependence between the magnetoresist ivity and the room temperature resistivity. Assuming the presence of nanome ter sized particles in the percolating conduction channels whose contributi ons are sensitive to temperature and the external magnetic field, we develo ped a phenomenological model to explain all the common features.