Berlin 2008 – scientific programme
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MA: Fachverband Magnetismus
MA 18: Poster I : Bio Magn. (1-2); Mag.Imgaging (3-9); Magn. Semiconductors (10-16); Half Metals & Oxides (17-20); Coupl.Phenomena (21-27); Magn. Mat. (28-41); Micro & Nanostr. Magn. Materials (42-61); Micro Magn. (62-64); Surface Magnetism (65-70); Transport Phenomena (71-85)
MA 18.49: Poster
Tuesday, February 26, 2008, 15:15–18:30, Poster E
XMCD studies of FePt nanocrystals — •Daniela Nolle1, Eberhard Goering1, Liberato Manna2, Albert Figuerola2, Thomas Tietze1, Sebastian Brück1, and Gisela Schütz1 — 1Max-Planck-Institute for Metal Research, Heisenbergstr. 3, 70569 Stuttgart, Germany — 2National Nanotechnology Laboratory of CNR-INFM, Unità di Ricerca IIT, Distretto Tecnologico ISUFI, via per Arnesano km. 5, I-73100 Lecce, Italy
We have investigated bi-magnetic FePt hybrid nanocrystals, prepared in a "one-pot" technique, using X-ray magnetic circular dicroism (XMCD). These hybrid nano crystals consist of a metallic FePt core with fcc structure and an iron oxide shell with inverse spinell crystal structure, which is a mixture of magnetite (Fe3O4) and maghemite (γ-Fe2O3). The investigations were performed both surface-sensitive in total electron yield mode (TEY) and bulk-sensitive in transmission.
These spectra have been analysed in terms of a linear superposition of suitable reference data. So we could determine the radial composition of the nanocrystals and the contributions of the constituents to the overall magnetic moment. A comparison between TEY and transmission measurements shows that the iron oxide shell is mainly maghemite like, while the surface magnetisation has predominantly magnetite character. With decreasing temperature the XMCD transmission results are in perfect agreement to bulk sensitive SQUID-measurements, while the surface exhibits a stronger increased magnetic moment at low temperatures.