Regensburg 2013 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 17: Magnetic Particles and Clusters (jointly with CPP, BP)
MA 17.10: Vortrag
Dienstag, 12. März 2013, 12:30–12:45, H22
Magnetic correlations in 3D ordered nanoparticle assemblies — Elisabeth Josten1, •Oleg Petracic1, Ulrich Rücker1, Artur Glavic2, Valeria Lauter2, Erik Wetterskog3, German Salazar-Alvarez3, Lennart Bergström3, and Thomas Brückel1 — 1JCNS-2 and PGI-4, Forschungszentrum Jülich, Germany — 2Oak Ridge Natl Lab, Quant. Cond. Mat. Div, Oak Ridge, TN 37831 USA — 3Stockholm Universitet, Department of Materials and Environmental Chemistry, Stockholm, Sweden
Nanoparticle superlattices can be considered as novel type of materials with controllable electronic, optical and magnetic properties. Understanding the magnetic behavior of ordered nanoparticle arrays is an important step towards the controlled design of e.g. novel devices. We have studied γ-Fe2O3 nanocubes and nanospheres with a diameter ≈ 10 nm. The particles have been deposited on a Si substrate to form highly ordered superstructures (mesocrystals) using a drop casting method. Structural characterization has been carried out using SEM, AFM, TEM and GISAXS. Depending on the shape of the particles, the arrays show mesostructures with bct or fcc symmetry with relatively long structural correlation lengths of 2-10 µm. In order to investigate magnetic inter-particle correlations we have employed grazing incidence neutron scattering experiments in reflectometry mode at the JCNS-instrument TREFF at the FRM II in Garching and in GISANS mode at the Magnetism Reflectometer at the SNS in Oak Ridge. These experiments yielded the degree of magnetic correlation for the in-plane and out-of-plane directions at different applied fields.