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MA: Fachverband Magnetismus
MA 37: Magnetic Imaging Techniques
MA 37.1: Vortrag
Donnerstag, 20. März 2025, 15:00–15:15, H16
Magnetic particle spectroscopy of ferrite nanoparticles: Controlling the Néel to Brownian relaxations — •Ondřej Kaman1, Tereza Voltrová1,2, Lenka Kubíčková1,2, Ali Hassan1, Pavel Veverka1, Kyo-Hoon Ahn1, Karel Knížek1, Denisa Kubániová2, and Jaroslav Kohout2 — 1FZU - Institute of Physics, CAS, Praha, Czech Republic — 2Faculty of Mathematics and Physics, Charles University, Praha, Czech Republic
The Fourier transform of the magnetization response of a suspension of magnetic particles to a sinusoidal AC magnetic field provides so-called magnetic particle spectrum, i.e., a series of higher harmonics that originate in the non-linear M(H) dependence. This characteristic is crucial for magnetic particle imaging (MPI), which is an emerging technique employing magnetic particles, typically in the superparamagnetic state, as exogeneous tracers for medical imaging. The magnetization dynamics of such tracers is governed by two distinct mechanisms, the Néel relaxation of magnetic moments and the Brownian rotation of whole particles. The present study is based on a series of hydrothermally prepared and thoroughly characterized (XRD, XRF, TEM, SQUID magnetometry) samples of Co1−xNixFe2O4 particles with x=0–0.5 and the mean crystallite size of 8–9 nm. Their silica-coated clusters, forming colloidally stable aqueous suspensions, were prepared, and MPI study was performed by means of an in-house built system (interchangeable coils impedance-matched to ∼10, 15, 25, 35, and 50 kHz; magnetic field up to 20 mT).
Keywords: magnetic nanoparticles; magnetic particle imaging