Analysis of the thickness dependence of magnetic properties and interparticle interaction of granular films

In this paper, we study the interparticle interaction among the magnetic nanoparticles in granular films and how this interaction affects their magnetic properties. Attention has been paid to the thermal stability and coercivity of Cu₈₀Co₂₀ granular thin films with thickness from 7-400 nm. It is found that the blocking temperature and coercivity increase when the film thickness increases until the thickness is larger than a critical value. These effects have been analyzed due to the magnetic dipolar interaction. Our analysis shows that the interaction energy is a function of film thickness. The magnetic long-range order has been introduced in our model. Theoretical approaches of the thickness dependence of blocking temperature and coercivity have been given and they are in agreement with the experimental data