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 Francisco de Quito

Otro; 2018 IEEE Magnetics Summer School; 2018

IEEE Magnetics Society

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 thedescription 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 implies important effects concerning the hysteresis of each nanoparticle and hyperthermia, as we have discussed in the conclusions of this work. One of the most important is the fact that the dipolar interaction 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. 320e312-5[2] Rosensweig R E 2002 Heating magnetic fluid with alternating magnetic field J. Magn. Magn. Mater. 252 370-4