Magnetic particle hyperthermia: Power losses under circularly polarized field in anisotropic nanoparticles

TL;DR

This study uses the Landau-Lifshitz-Gilbert equation to analyze how anisotropy affects energy losses in magnetic nanoparticles under circularly polarized fields, with implications for optimizing hyperthermia cancer therapy.

Contribution

It generalizes previous isotropic models to include anisotropy effects on power losses, providing insights for improving hyperthermia treatment efficiency.

Findings

Anisotropy reduces energy loss per cycle compared to isotropic nanoparticles.

Isotropic nanoparticles exhibit better heating efficiency at low frequencies.

Thermal fluctuations may influence dissipation mechanisms.

Abstract

The deterministic Landau-Lifshitz-Gilbert equation has been used to investigate the nonlinear dynamics of magnetization and the specific loss power in magnetic nanoparticles with uniaxial anisotropy driven by a rotating magnetic field, generalizing the results obtained for the isotropic case found in [P. F. de Chatel, I. Nandori, J. Hakl, S. Meszaros and K. Vad, J. Phys.: Condens. Matter 21, 124202 (2009)]. As opposed to many applications of magnetization reversal in single-domain ferromagnetic particles where losses must be minimized, in this paper, we study the mechanisms of dissipation used in cancer therapy by hyperthermia which requires the enhancement of energy losses. We show that for circularly polarized field, the loss energy per cycle is decreased by the anisotropy compared to the isotropic case when only dynamical effects are taken into account. Thus, in this case, in the low frequency limit, a better heating efficiency can be achieved for isotropic nanoparticles. The possible role of thermal fluctuations is also discussed. Results obtained are compared to experimental data.