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MA: Fachverband Magnetismus
MA 19: Poster I (Bio- and Molecular Magnetism/ Magnetic Particles and Clusters/ Micro- and Nanostructured Magnetic Materials/ Magnetic Materials/ Multiferroics/ Magnetic Shape Memory Alloys/ Electron Theory of Magntism/ Spincaloric Transport/ Magnetic Coupling and Exchange Bias/ Magnetization Dynamics/ Micromagnetism and Computational Magnetics)
MA 19.10: Poster
Tuesday, March 15, 2011, 10:45–13:00, P2
Are spin and orbital contributions to magnetic moments of FePt nanoparticles size-dependent? — •Luyang Han, Ulf Wiedwald, and Paul Ziemann — Institut für Festkörperphysik, Universität Ulm, A.-Einstein-Allee 11, 89069 Ulm, Germany
FePt nanoparticles (NPs) have attracted much interest due to their potential applications as well as its intriguing properties in basic research [1]. For magnetic NPs in general it is often observed that the magnetic properties deviate from the corresponding bulk behavior for diameters well below 10 nm. In this contribution we report on spin and orbital magnetic moments of FePt NPs with diameter of 3-10 nm prepared via reverse micelles [2]. X-ray magnetic circular dichroism (XMCD) reveals an increase of the ratio of orbital and spin magnetic moments after annealing at 700 ∘C for 30 min correlated with the emerging L10 phase. For this ratio, however, no significant size-dependence could be found. On the other hand, extended annealing above 700 ∘C leads to a decreasing ratio of orbital-to-spin moment. Since XMCD is quite surface sensitive, this indicates that besides the L10 phase formation annealing induced changes of the chemical surface composition may influence orbital-to-spin ratio of magnetic NPs.
[1]S. Sun, Adv. Mater., 18, 393, (2006)
[2]U. Wiedwald et al., Beilstein J. Nanotechnol., 1, 24, (2010)