Neutron diffraction from superparamagnetic colloidal crystals

M. Ličen, I. Drevenšek-Olenik, L. Čoga, S. Gyergyek, S. Kralj, M. Fally, C. Pruner, P. Geltenbort, U. Gasser, G. Nagy, J. Klepp

Journal of Physics and Chemistry of Solids 110 (2017) 234–240.

Abstract

We fabricated a superparamagnetic ordered structure via self-assembly of a colloidal crystal from a suspension of maghemite nanoparticles and polystyrene beads. Such crystals are potential candidates for novel polarizing beamsplitters for cold neutrons, complementing the available methods of neutron polarization. Different bead sizes and nanoparticle concentrations were tested to obtain a crystal of reasonable quality. Neutron diffraction experiments in the presence of an external magnetic field were performed on the most promising sample. We demonstrate that the diffraction efficiency of such crystals can be controlled by the magnetic field. Our measurements also indicate that the Bragg diffraction regime can be reached with colloidal crystals.

URL: http://www.sciencedirect.com/science/article/pii/S0022369716312422

Keywords: Colloidal crystals, Superparamagnetic nanoparticles, Neutron scattering

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