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MA: Fachverband Magnetismus
MA 17: Invited Talks Rellinghaus / Antoniak
MA 17.1: Invited Talk
Tuesday, February 26, 2008, 14:00–14:30, EB 301
FePt nanomagnets from the gas phase — •Bernd Rellinghaus, Elias Mohn, Ute Queitsch, and Ludwig Schultz — IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany
Unlike other approaches, the gas phase preparation of nanoparticles provides the advantage to thermally anneal such particles prior to their deposition onto a substrate. Control of the in-flight annealing conditions thereby allows to either thermally equilibrate likewise prepared nanosized materials or to adjust metastable phases on them. The potential and the challenges of this approach for the preparation of metallic nanomagnets which may be used as future materials in high density magnetic data storage media will be reviewed.
FePt is still among the most intensively studied materials when it comes to pushing the superparamagnetic limit towards minimum particle sizes. It will be demonstrated that gas phase synthesis allows for the preparation of L10 ordered FePt nanoparticles without any post-deposition thermal treatment. Along with the formation of the L10 phase goes a significant increase of the switching fields to above 1T even at room temperature. The effect of varying annealing times and temperatures on the particles’ structure provides substantial insight into the ordering mechanism. Pre-conditioned substrates may be used to initiate a regular arrangement of gas-phase prepared nanomagnets via self-assembly. Although these findings are promising in view of applications, obstacles such as the widening of the particle size distribution as a consequence of the in-flight annealing or a still limited degree of L10 order in the annealed particles are yet to be overcome.