Dresden 2011 – scientific programme
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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 19.76: Poster
Tuesday, March 15, 2011, 10:45–13:00, P2
Investigation of the exchange coupling between Co nanoparticles and a Co/NiMn exchange bias system — •Benjamin Riedmüller, Balati Kuerbanjiang, and Ulrich Herr — Institut für Mikro- und Nanomaterialien, Universität Ulm
In this work, the exchange coupling of Co nanoparticles deposited on a layered Co/NiMn exchange bias system is studied. First the Co/NiMn stack was deposited on a 10 nm thick Ru layer by DC magnetron sputtering. All samples were covered by a 4 nm thick Ta layer to prevent oxidation. For transforming NiMn from the paramagnetic fcc phase to the antiferromagnetic fct phase the samples were annealed in vacuum conditions for 10 min at 360 ∘C with an external magnetic field of +3 kOe. Different thicknesses of NiMn and Co were used to optimize the interface coupling strength. For 66 nm NiMn a coupling strength of Jex = 0.3 mJ/m2 was found as a maximum value. Spherical Co nanoparticles of 20 nm in diameter were prepared by Inert Gas Condensation technique. After deposition of the Co nanoparticles on top of the Co/NiMn stack a drastic reduction of the exchange bias field was observed. This effect depends on the particle coverage of the samples. Following the Meiklejohn-Bean description of the exchange bias effect this can be interpreted as a local increase of the film thickness due to exchange coupling between the the nanoparticles and the Co film.