Effects of magnetic interparticle coupling on the blocking temperature of ferromagnetic nanoparticle arrays

In this work we report on the study of the magnetic properties of 2D arrays and 3D dispersions of colloidal iron oxide nanoparticles prepared by Langmuir-Blodgett technique and by dilution in paraffin wax solid solution, respectively. The influence of magnetic interparticle coupling on the superparamagnetic relaxation behavior was investigated by means of DC magnetization measurements. A quantitative analysis of the field dependence of the blocking temperature and the role of the interparticle coupling is presented. We explain our results using a phenomenological model based on the random anisotropy and micromagnetic theories that account for particle coupling effects in the superparamagnetic properties. (c) 2007 Elsevier B.V. All rights reserved.