Interparticle interactions in coupled Au- Fe3 O4 nanoparticles

Abstract

Complex ac susceptibility measurements are reported on composite Au- Fe3 O4 nanoparticles of two different configurations-the so-called "dumbbell" and "flower" configurations. The frequency-dependent blocking temperature was fitted to two separate models in an attempt to understand the relaxation and the role of interactions present in the nanoparticle arrays. While the Ńel-Arrhenius model failed to accurately describe the blocking behavior of both types of particles, the Vogel-Fulcher model was shown to fit the dumbbell particles indicating the importance of weak interparticle interactions in this system. The flower nanoparticles, however, failed to yield physical fit parameters for both models, indicating that the interactions present in these particles are not solely dipolar but likely associated with competing intraparticle interactions. Radio-frequency transverse susceptibility measurements also confirm these features. © 2009 American Institute of Physics.