Scaling behavior of the giant magnetoresistance of magnetic aggregates - art. no. 134422

We study numerically the giant magnetoresistance (GMR) of magnetic nanopart icle aggregates formed on a planar substrate by a diffusion process that is driven by the magnetostatic dipolar interactions between the particles. Th e growth of aggregates is modeled by a diffusion limited cluster aggregatio n model and the GMR of the assembly is expressed in terms of the short rang e spin correlation function. The latter is obtained by a Monte Carlo simula tion. We show that the spin correlation function of the aggregates can be d escribed by a scaling law that involves the fractal dimensionality of the s tructure. The formation of aggregates causes a large reduction of the low-f ield GMR because the role of interparticle dipolar interactions is enhanced due to the chainlike morphology of the aggregates.