Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 1: Magnetic nanoparticles (joint session MA/CPP)
MA 1.6: Vortrag
Montag, 12. März 2018, 11:00–11:15, H 0112
Distributed heat production in clusters of magnetic nanoparticles — Paola Torche1, David Serantes2, Sergiu Ruta3, Roy Chantrell3, and •Ondrej Hovorka1 — 1University of Southampton, Southampton, UK — 2Universidade de Santiago de Compostela, Santiago de Compostela, Spain — 3University of York, York, UK
We address the issue of quantifying the heat produced by a single magnetic nanoparticle (MP) embedded within an interacting MP cluster. This is relevant for MP hyperthermia considered as a modality for enhancing cancer therapies, where it becomes necessary to understand the distribution of heat production across a MP aggregate inside a living cell. The heat produced by MPs subject to time-varying external magnetic field can be determined from the area of the hysteresis loop. However, at the single-particle level of description, the magnetization of a MP undergoes a fluctuating stochastic process and the meaning of the hysteresis loop becomes ambiguous, as suggested also experimentally. It is then unclear how to quantify the heat production, especially if the interactions between MPs cannot be neglected.
We use the modern stochastic thermodynamics in combination with the Néel-Arrhenius theory of thermal relaxation of MPs to establish the relationship between the fluctuating work and entropy (heat) produced along the fluctuating magnetization trajectories of MPs. By considering the dipolar chains of MPs, we demonstrate a practical recipe for quantifying the heat produced by a single MP embedded within a chain, which then allows to map heat production distributions along the chains.