Giant Hall Effect and Spin-Dependent Transport in Granular NiFe-SiO2 Films

In granular NiFe-SiO2 films which display giant Hall effect, extraordinary Hall resistivity ρxys, normal Hall resistivity ρxyo, and magnetoresistivity δρ, were all found to follow power lav dependencies on resistivity ρ. Namely, -ρxys ∼ ρ0.81, -ρxyo ∼ ρ0.64 and -δρ ∼ ρ1.15. We propose that the presence of nanometer sized particles in the percolating conduction channels gives rise to I giant enhancement for both ordinary and extraordinary Hall effect in magnetic metal-insulator nanocomposite films. This physical picture describes qualitatively well the general features of GHE, and its correlation with resistivity and magnetoresistivity.