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MA: Magnetismus

MA 32: Magnetic Particles / Clusters

MA 32.7: Vortrag

Donnerstag, 30. März 2006, 16:45–17:00, HSZ 401

Preparation and characterisation of L10-FePt nanoparticles in the gas phase. — •Olga Dmitrieva, Günter Dumpich, Jöchen Kästner, and Mehmet Acet — Experimentalphysik, AG Farle, Universität Duisburg-Essen, 47048 Duisburg

FePt nanoparticles with sizes between 5-10 nm are prepared by inert gas condensation using DC sputtering and subsequent flight-annealing through a furnace set to temperatures in the range 600^∘C 1200^∘C. Morphology and structure of the obtained nanoparticles depend on the nucleation pressure and annealing temperature. The process at a nucleation pressure of 0.5 mbar yields multiply twinned icosahedral particles, whereas at 1.0 mbar, polycrystalline nanoparticles are observed. The desired chemically ordered L10-phase with high magneto-crystalline anisotropy in some particles was detected using high resolution transmission electron microscopy (HRTEM). With the addition of nitrogen to the sputtering gas, the formation of the icosahedral structure is suppressed, predominantly single crystalline L10-ordered nanoparticles are formed. To verify the incorporation of nitrogen into the atomic structure, we use electron energy loss spectroscopy (EELS) and X-Ray absorption spectroscopy (XAS). Work supported by DPG (SFB445).