Ferromagnetic resonance in magnetic nanoparticle assemblies

Nanoparticle physics is of broad interest in the scientific community, offering an enormous range of potential applications and possibilities for testing fundamental science. In this paper we consider the magnetic properties of nanosized particles in a non-magnetic matrix. In particular we shall discuss how the technique of ferromagnetic resonance (FMR) can be applied to nano-systems. We shall give an outline of the basic FMR theory to account for these effects and show some examples of experimental data. We have used the γ-Fe2O3 nanoparticle assembly as a model system for FMR studies where we apply the dipole–dipole interaction theory to our results. We show that these considerations lead to an overall assembly shape anisotropy which results from the spatial distribution of particles.