Regensburg 2010 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 23: Micro- and Nanostructured Magnetic Materials III
MA 23.2: Vortrag
Donnerstag, 25. März 2010, 10:30–10:45, H3
Determining the magnetic properties of small assemblies of nanodots — •Simon Hesse1, Matthias Jacobi1, André Kobs1, Daniel Stickler1, Holger Stillrich1, Alexander Neumann1, Andreas Meyer2 und Hans Peter Oepen1 — 1Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany — 2Institut für Physikalische Chemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany
We have successfully developed a technique to fabricate nanodots of variable size and varying magnetic properties based on self-organized assembling of diblock-copolymer micelles on magnetic multilayers [1]. The micelles are filled with silica cores, which are used as shadow mask for subsequent Ar+ ion milling. The method allows for creating superparamagnetic as well as ferromagnetic Co/Pt nanodots. The magnetic properties are investigated via magneto-optical Kerr Effect (MOKE) and anomalous Hall Effect (AHE). Due to the free scalability of the AHE it is possible to measure very small ensembles of dots. To achieve these small ensembles Hall cross geometries have been created via ion beam lithography (IBL). Varying the size of the crossing area and the filling factor of silica cores enables us to adjust the number of dots to measure. It has been found that the AHE has an extremely high sensitivity that makes it possible to identify magnetization curves of the dots down to filling factors of about 5 %. Hence, we report on AHE measurements of the magnetic behaviour of less than 10 dots.
[1] H. Stillrich et al., Adv. Funct. Mat. 18, 76 (2008)