Effects of magnetic interparticle coupling in the blocking temperature of granular Co multilayers

In order to study the influence of magnetic interactions on the blocking temperature of magnetic nanoparticles, magnetization measurements were carried out on a discontinuous Co/SiO2 multilayer. The observed field dependence of the blocking temperature does not fit any of the non-interacting laws commonly used to describe this behavior. We applied a generalized model which considers a field-dependent magnetic correlation length. This model explains well the experimental results and can be used in other nanoparticulate systems.