Unified model of hyperthermia via hysteresis heating in systems of interacting magnetic nanoparticles

TL;DR

This study develops a comprehensive model for hyperthermia in magnetic nanoparticles, revealing how inter-particle interactions influence heating efficiency, especially near the transition between superparamagnetic and hysteretic regimes.

Contribution

It introduces a kinetic Monte-Carlo method that accounts for interactions and large driving fields, surpassing standard linear response theory in modeling hyperthermia.

Findings

Interactions can enhance or suppress heating power unexpectedly.

Optimal heating occurs near the transition between regimes.

Standard theory cannot predict interaction effects accurately.

Abstract

We present a general study of frequency and magnetic field dependence of the specific heat power produced during field-driven hysteresis cycles in magnetic nanoparticles with relevance to hyperthermia applications in biomedicine. Employing a kinetic Monte-Carlo method with natural time scales allows us to go beyond the assumptions of small driving field amplitudes and negligible inter-particle interactions, which are fundamental to applicability of the standard approach based on linear response theory. The method captures the superparamagnetic and fully hysteretic regimes and the transition between them. Our results reveal unexpected dipolar interaction-induced enhancement or suppression of the specific heat power, dependent on the intrinsic statistical properties of particles, which cannot be accounted for by the standard theory. Although the actual heating power is difficult to predict because of the effects of interactions, optimum heating is in the transition region between the superparamagnetic and fully hysteretic regimes.