N.C.S.R. "Demokritos"


Department of Materials Science

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Magnetic Ferrofluids

When magnetic nanoparticles are allowed to move in a carrier, driven by thermal agitation (Brownian motion) and their mutual interactions (magnetostatic), they tend to form well defined shapes such as chains and loops, or more complicated structures such as branching points and labyrinths, whose statistical morphology can be characterized as a fractal. The potential of systems with a non-magnetic liquid carrier, known as ferrofluids, in medical applications (drug delivery) and technological applications (magnetic field sensors) brings these systems at the frontiers of current scientific interest. The aggregation mechanism and the resulting fractal morphology depends on internal parameters (particle size distribution, magnetic moments, particle shape, interparticle interactions, particle-carrier interactions, particle density) and external conditions (temperature, applied field). In this project we model the aggregation mechanism of magnetic nanoparticles driven by magnetostatic (dipolar) interactions using the Diffusion Limited Cluster Aggregation model (DLCA). We study the rheology of the interacting nanoparticle assembly and relate their physical properties to the aggregate morphology. Systems of interest include, so far, 2 magnetic nanoparticle aggregates under application of an in-plane field. Physical properties such as magnetization, moment-moment correlation function and magneto-optical properties (refraction index) are characterized by scaling exponents that are strongly depended on the growth conditions of the aggregate.

Department of Materials Science, N.C.S.R. "Demokritos", 153 10 Aghia Paraskevi, Attiki, phone: +30 210 6503381, fax: +30 210 6519430
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