Efficiency of magnetic hyperthermia in the presence of rotating and static fields

• Main Authors: Iszaly, Zs, Lovasz, K, Nagy, I, Marian, I. G, Racz, J, Szabo, I. A, Toth, L, Vas, N. F, Vekony, V, Nandori, I
• Format: Journal Article
• Language: English
• Published: 12-07-2018
• Subjects: Physics - Medical Physics; Physics - Soft Condensed Matter
• DOI: 10.48550/arxiv.1706.07426

J. Magn. Magn. Mater. 466 (2018) 452 Single-domain ferromagnetic nanoparticle systems can be used to transfer
energy from a time-dependent magnetic field into their environment. This local
heat generation, i.e., magnetic hyperthermia, receives applications in cancer
therapy which requires the enhancement of the energy loss. A possible way to
improve the efficiency is to chose a proper type of applied field, e.g., a
rotating instead of an oscillating one. The latter case is very well studied
and there is an increasing interest in the literature to investigate the former
although it is still unclear under which circumstances the rotating applied
field can be more favourable than the oscillating one. The goal of this work is
to incorporate the presence of a static field and to perform a systematic study
of the non-linear dynamics of the magnetisation in the framework of the
deterministic Landau-Lifshitz-Gilbert equation in order to calculate energy
losses. Two cases are considered: the static field is either assumed to be
perpendicular to the plane of rotation or situated in the plane of rotation. In
the latter case a significant increase in the energy loss/cycle is observed if
the magnitudes of the static and the rotating fields have a certain ratio (e.g.
it should be one for isotropic nanoparticles). It can be used to
"super-localise" the heat transfer: in case of an inhomogeneous applied static
field, tissues are heated up only where the magnitudes of the static and
rotating fields reach the required ratio.