RECENT STUDIES OF SPIN DYNAMICS IN FERROMAGNETIC NANOPARTICLES
In recent years, the study of magnetic nanoparticle systems has received growing attention. With view to many applications, this area of scientific study shows enormous potential for growth. One central theme of this line of investigation is how the magnetic properties of nanoparticle assemblies are modified with respect to the bulk. Such differences in magnetic behavior are expected to arise from interparticle interactions, which will depend on the intervening non-magnetic matrix in which the particles are suspended, and from the size confinement effects, essentially due to the surface anisotropy of the particles. In addition to these fundamental effects, we also need to consider the superparamagnetic (SPM) behavior that is of great importance to the overall magnetic behavior of these systems. The SPM effects are strongly related to the overall magnetic anisotropy of the individual particles and have strong temperature dependences (Dormann et al., 1997).