The effect of dipolar interactions in clusters of magnetic nanocrystals

Abstract

Monte Carlo simulations are carried out to evaluate the effective magnetic moment μeff of clusters containing 100 magnetic nanocrystals (MNCs) in a low magnetic field. The true value of the initial magnetic susceptibility, i.e. χ0 δM/δH at zero field, can be easily assessed from μeff. Results show that dipolar interactions contribute to reduce the effective magnetic moment. Below a threshold value near the low-field region, clusters of MNCs with smaller diameters possess a larger effective magnetic moment per unit volume compared to clusters with larger MNCs. This is of particular interest for bio-sensing systems relying on the magnetic response of magnetic multi-core nanoparticles in the low-field region. © 2010 IOP Publishing Ltd.