Nanochains formation of superparamagnetic nanoparticles

We present simulations on the aggregation of nanometer sized polydispersed superparamagnetic particles under the application of an external magnetic field. We make use of a Monte Carlo method, using a cluster-moving approach, as previously used in literature for ferrofluids. van der Waals attraction and magnetic anisotropy are taken into account in the simulations. Chains elongated in the field direction are formed. The results are in good agreement with recent experimental results on nanochains made of iron oxide nanoparticles into polymer matrix, obtained with the application of a magnetic field during film deposition. The magnetization anisotropy of the nanocomposite film under dc magnetic field can be predicted within this simple model. © 2011 American Chemical Society.