Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 2: Micro and Nanostructured Magnetic Materials I

MA 2.5: Talk

Monday, February 25, 2008, 11:15–11:30, EB 301

CoPt alloy films on SiO₂ nanoparticle arrays — •Denys Makarov¹, Esteban Bermudez², Christoph Brombacher³, Fabiola Liscio⁴, Mireille Maret⁴, Oliver G. Schmidt², Günter Schatz¹, and Manfred Albrecht³ — ¹University of Konstanz, Department of Physics, 78457 Konstanz, Germany — ²IFW Dresden, 01069 Dresden, Germany — ³Chemnitz University of Technology, Institute of Physics, D-09107 Chemnitz, Germany — ⁴ENSEEG, Saint Martin d’Heres, France

Combining self-assembled SiO₂ nanoparticle arrays with magnetic film deposited onto the particles, enables an elegant possibility to create magnetic nanostructure arrays with defined magnetic properties. In this regard, materials such as CoPt alloy are of particular interest due to their large magnetic anisitropy required for thermal stability in the high density magnetic recording applications. In order to induce high perpendicular magnetic anisotropy in CoPt alloys, the L1₀ phase with (001) texturing is required. For this purpose, a 10nm thick MgO(001) seed layer was introduced. Results on planar amorphous SiO₂ substrates reveal an uniaxial out-of-plane magnetic anisotropy and saturation magnetization for the CoPt alloy grown at 450^∘C of about 5x10⁵J/m³ and 800kA/m. These properties were transfered to CoPt alloy deposited onto arrays of SiO₂ particles with diameters down to 50nm. The formed CoPt nanocaps are in a magnetic single domain state with a large out-of-plane coercivity, which increases with decreasing particle size. In this presentation, the structural and magnetic properties will be discussed and compared to the planar film.