Berlin 2015 – scientific programme
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MA: Fachverband Magnetismus
MA 54: Magnetic Coupling Phenomena
MA 54.7: Talk
Friday, March 20, 2015, 11:00–11:15, EB 301
Comparison of magnetic properties in amorphous and crystalline Fe/Fe-O core/shell nanoparticles — •Anil Kumar P.1,2, Gurvinder Singh3, Wilhelm R Glomm4, Davide Peddis5, Erik Wahlstrom6, and Roland Mathieu1 — 1Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala,Sweden — 2Present Address: Fakultat Physik, Universitat Duisburg-Essen, Duisburg 47048, Germany — 3Department of Chemical Engineering, NTNU, N-7491, Trondheim, Norway — 4SINTEF Materials and Chemistry, Biotechnology and Nanomedicine Sector, Trondheim, N-7491 Trondheim, Norway — 5ISM-CNR, Area della Ricerca, Via Salaria km 29 500, C.P. 10-00016 Monterotondo Scalo, Roma, Italy — 6Department of Physics, NTNU, N-7491, Trondheim, Norway
Fe and Fe-O nanoparticles form an important part of several biomedical and technological applications. We report on the magnetic properties of amorphous Fe/Fe-O core/shell nanoparticles compared to those of a reference system with crystalline Fe/Fe-O core/shell nanoparticles. These nanoparticles are prepared by thermal decomposition and the nature of particles, amorphous or crystalline, is controlled by the choice of the ligand/surfactant. The crystalline Fe/Fe-O nanoparticles remain blocked until room temperature and exhibit small exchange bias effect. However, the amorphous Fe/Fe-O nanoparticles show substantial exchange bias and collective magnetic behavior with features of magnetic frustration and disorder reminiscent of spin/superspin glass systems. We discuss the origin of these effects.*Conference attendance supported by the EU-project NU-MATHIMO.