RF dynamics in nanoparticle systems with tuned strength of interactions

Summary form only given. The dynamics of magnetic nanoparticle systems is a subject of considerable interest due to their fundamental and technological interest. The properties of such systems are strongly modified compared to the bulk, due to granular texture and the small size of the grains. In this paper we present a study on the magnetic properties of different samples of Co nanoparticles dispersed in different volume fractions in a wax matrix. Structural and morphological analysis of the Co nanoparticles systems was performed by TEM and light scattering experiments. RF transverse susceptibility (TS) experiments at various temperatures, ac susceptibility in the frequency range (10 Hz, 10/sup 4/ Hz) and various field and temperature dependent magnetization processes were used in order to investigate dynamics in nanoparticle systems. In the paper the experimental observed effect of inter-action on TS curves is very well explained by a new micromagnetic model of TS based on the Landau-Lifshitz-Gilbert equation.