International Journal on Magnetic Particle Imaging
Vol 6 No 2 Suppl. 1 (2020)
https://doi.org/10.18416/IJMPI.2020.2009005

Proceedings Articles

Individual observation of Néel and Brownian relaxations in magnetic nanoparticles

Main Article Content

Satoshi Ota  (Shizuoka University), Yasushi Takemura  (Yokohama National University)

Abstract

Magnetic relaxation divided into the Néel and Brownian regimes determines the magnetization dynamics. To develop the signal intensity and resolution of magnetic particle imaging, understanding the magnetization dynamics was required. In this study, the Néel and Brownian relaxations were individually evaluated. The two-step magnetization response of magnetic nanoparticles dispersed in a fluid as the Brownian regime occurred after the Néel regime was observed by applying a fast responding pulse field. To clarify the magnetic relaxation in detail, it is necessary to individually observe the Néel and Brownian relaxations in the superposition system. By fitting the theoretical calculation to the measured time evolution of the magnetization response, we isolated Néel and Brownian relaxations from the experimentally observed superposition relaxation system. Moreover, the effect of dipole interactions on Néel and Brownian relaxation were confirmed by measuring the dependence of magnetization responses on the particle concentration in a magnetic fluid.
 
Int. J. Mag. Part. Imag. 6(2), Suppl. 1, 2020, Article ID: 2009005, DOI: 10.18416/IJMPI.2020.2009005

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