Nonequilibrium response of magnetic nanoparticles to time-varying magnetic fields: contributions from Brownian and Néel processes

Ilg, P. ORCID: https://orcid.org/0000-0002-7518-5543 (2024) Nonequilibrium response of magnetic nanoparticles to time-varying magnetic fields: contributions from Brownian and Néel processes. Physical Review E, 109 (3). 034603. ISSN 2470-0053 doi: 10.1103/PhysRevE.109.034603

Abstract/Summary

Many technical and biomedical applications of magnetic nanoparticles rely on their response to time–varying magnetic fields. While well–established models exist for either immobile or thermally blocked nanoparticles, the intermediate regime where Brownian as well as Néel relaxation occur at the same time is less well explored. Here, we use an efficient model that allows us to study the non-linear dynamics of individual magnetic nanoparticles in response to different time–varying magnetic fields over a broad range of field parameters, taking into account both relaxation mechanisms. We provide quasi–exact solutions for the longitudinal dynamics as well as approximate formulae from dynamic mean–field theory. Our results are relevant e.g. for magnetorelaxometry, magnetic fluid hyperthermia and magnetic particle imaging. For these example applications, we show that the ratio of characteristic Brownian to Néel relaxation time can have a profound impact on characteristic response quantities, especially at large field strengths.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/115156
Identification Number/DOI	10.1103/PhysRevE.109.034603
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Mathematics and Statistics
Publisher	American Physical Society
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