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MM: Fachverband Metall- und Materialphysik

MM 26: Functional Materials V: Functional Materials

MM 26.3: Vortrag

Dienstag, 17. März 2015, 12:15–12:30, TC 010

Assembly of magnetic nano-particles close to a solid wall — •apurve saini, vassilios kapaklis, and max wolff — material physics, department of physics and astronomy, uppsala university, uppsala, sweden

Ferro-fluids are liquids with magnetic nano-particles dispersed in a solvent and show a super-paramagnetic behavior. The magnetic moment makes the particles sensitive to magnetic fields. The application of such a field can drive self-assembly and result in e.g. smectic like ordering.

We investigated the adsorption of magnetic nano-particles close to a ferrofluid-SiO2 interface as a function of external magnetic and flow fields. The particles are stabilized by surface coatings, which makes them extremely sensitive to the termination of a solid boundary and mono- or multilayers can form. The surface energy and polarity of the solid boundary is tuned by self-assembled monolayers.

In situ neutron reflectometry and grazing incidence has been utilized to obtain a detailed microscopic picture of this ordering phenomenon. Thus, the equilibrium as well as kinetics of the self-assembly is studied systematically. Both magnetic fields as well as flow facilitate pronounced layering at the interface,revealing a controlled growth of magnetically nanostructured interfaces on the time scales of hours.