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Dresden 2006 – scientific programme

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MA: Magnetismus

MA 32: Magnetic Particles / Clusters

MA 32.8: Talk

Thursday, March 30, 2006, 17:00–17:15, HSZ 401

Enhanced orbital magnetism in oxide-free FePt nanoparticles — •C. Antoniak1, K. Fauth2,3, H.-G. Boyen4, U. Wiedwald4, F. Wilhelm5, A. Rogalev5, M. Spasova1, J. Lindner1, M. Acet1, and M. Farle11Fachbereich Pysik, Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg — 2MPI für Metallforschung, Heisenbergstr. 3, D-70689 Stuttgart — 3Experimentelle Physik IV, Universität Würzburg, Am Hubland, D-97074 Würzburg — 4Abteilung Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, D-89069 Ulm — 5European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, B.P. 220, F-38043 Grenoble

Wet chemically synthesised Fe50Pt50 particles with a mean diameter of 6.3 nm deposited on a naturally oxidised Si substrate have been structurally and magnetically characterised. By a soft hydrogen plasma treatment, the oxide shell and the organic ligands surrounding the chemically disordered particles in the as prepared state were removed and pure metallic x-ray absorption and magnetic circular dichroism spectra were measured at both the Fe and Pt L3,2 edges. After annealing for 30min at 600C in a hydrogen atmosphere of 5 Pa, the coercive field increased by a factor of 6. This indicates the formation of the chemically ordered L10 phase and is accompanied by an enhancement of the orbital magnetic moment at the Fe sites by more than 300%, whereas the magnetic moments at the Pt sites remain largely unchanged.
This work was supported by the BMBF (05 ES3XBA/5), the ESRF, the DFG (SFB 445) and the EU (MRTN-CT-2004-0055667, SyntOrbMag).

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