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MA: Fachverband Magnetismus

MA 17: Invited Talks Rellinghaus / Antoniak

MA 17.2: Hauptvortrag

Dienstag, 26. Februar 2008, 14:30–15:00, EB 301

Influence of composition inhomogeneities and symmetry reduction on the magnetism of FePt nanoparticles — •Carolin Antoniak — Fachbereich Physik and Center for Nanointegration, Universität Duisburg-Essen, Lotharstr. 1, 47048 Duisburg

The magnetic properties of nanoparticles may differ significantly from those of the corresponding bulk material. In the case of bimetallic alloys, not only the break of symmetry at the surface but also local deviations from the averaged composition should be taken into account for data interpretation. For wet-chemically synthesised, oxide-free FePt nanoparticles, the break of symmetry at the surface, changes in the crystal symmetry [1] and the inhomogeneous composition [2] influence the magnetic properties, yielding reduced effective spin magnetic moments and an enhanced orbital magnetism at the Fe sites with respect to the bulk material. The experimental results presented in this talk will also be discussed in terms of lattice relaxations [3] and recent results of ab-initio calculations concerning the energetics of different stable and metastable particle morphologies [4].

In collaboration with K. Fauth, F. Wilhelm, A. Rogalev, U. Wiedwald, H.-G. Boyen, M. Cerchez, O. Dmitrieva, A. Trunova, M. Acet, M. Spasova, J. Lindner, M. Farle and S. Sun. Financially supported by the DFG (SFB445), the BMBF, the EU and the ESRF.

[1] C. Antoniak et al., Phys. Rev. Lett. 97, 117201 (2006)

[2] C. Antoniak, M. Farle, Mod. Phys. Lett. B 21, 1111 (2007)

[3] R. M. Wang et. al., Phys. Rev. Lett., accepted

[4] M. E. Gruner et al., Phys. Rev. Lett., submitted