Magnetic hyperthermia: the influence of dipolar interactions in a magnetosome-like nanoparticle system

VALDÉS D.P.; DE BIASI E.; LIMA JR. E.; ZYSLER R.D.

Simposio; XXIII Latin American Symposium on Solid State Physics; 2018

 In this work we present a study of dipolar interactions in a magnetosome-like nanoparticle system, and their influence on hyperthermia experiments. We have modeled the system as a collection of identical nanoparticles arranged along rndomly-oriented chains. We assume that the effective field that felt by a particle is mainly given by the interaction with other particles in the same chain. Due to the morphological characteristics of the samples, we have considered  only Neel relaxation as the mechanism of energy absorption, discarding Brown relaxation mechanism. The magnetic behavior of the particles is described by a previous model  that considers the effects of temperature, as well as the frequency of the field swept in the experiment. In this model, which goes beyond the description of the linear response theory, the magnetic field is corrected considering interparticle interactions. We have studied the parallel and perpendicular components of the dipolar magnetic field regarding the external one. Our simulations showed that the particles corresponding to the ends of the chains feel effects due to the dipolar interactions differnt than those that the particles in the central part of the chains feel. This, in fact, implies important effects, which can be tuned, concerning the hysteresis of each nanoparticle and hyperthermia, as we have discussed in the conclusions of this work. One of the most important conclusions is the fact that the dipolar interaction in these kind of systems can help to improve the hyperthermia significantly for nanoparticle systems which can originally be far from the ideal conditions for hyperthermia experiments.