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MA: Fachverband Magnetismus

MA 49: POSTER II

MA 49.6: Poster

Thursday, March 19, 2015, 15:00–18:00, Poster A

Structural and magnetic properties of self-assembled 3D nanoparticle macrocrystals — •Michael Smik, Elisa Volkmann, Genevieve Wilbs, Emmanuel Kentzinger, Jörg Persson, Ulrich Rücker, Oleg Petracic, and Thomas Brückel — Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich

We have refined self-assembly methods for the fabrication of 3D nanoparticle ’macrocrystals’ composed of spherical iron oxide nanoparticles with 15 nm diameter. The macrocrystals were prepared using centrifuge assisted sedimentation with optimized temperature, centrifugation length and post-centrifugation procedures. Fabrication of macrocrystals up to 300 µm in size was possible. The samples were characterized using scanning electron microscopy (SEM) and grazing incidence small angle x-ray scattering (GISAXS) on single macrocrystals. The GISAXS experiments were performed at the new in-house instrument ’GALAXI’ (Gallium Anode Low-Angle X-ray Instrument) and reveal close-packed hexagonal ordering with very large coherence lengths. Zero field cooled (ZFC) and field cooled (FC) magnetization curves have been recorded. They show pronounced inter-particle collective ordering due to dipole-dipole interactions.