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

DANIELA P. VALDÉS; EMILIO DE BIASI; ENIO LIMA JR.; ROBERTO D. ZYSLER

San Carlos de Bariloche

Simposio; XXIII Latin American Symposium on Solid State Physics (SLAFES XXIII); 2018

Organizing Committee

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 randomly-oriented chains. We assume that the effective field 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 Néel relaxation as the mechanism of energy absorption, discarding Brown relaxation mechanism. The magnetic behavior of the particles is described by a previous model[1] 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[2], 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 different 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.[1] De Biasi E, Zysler R D, Ramos C A and Knobel M 2008 A new model to describe the crossover from superparamagnetic to blocked magnetic nanoparticles J. Magn. Magn. Mater. 320 e312-5[2] Rosensweig R E 2002 Heating magnetic fluid with alternating magnetic field J. Magn. Magn. Mater. 252 370-4