Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 25: Micro- and Nanostructured Magnetic Materials II
MA 25.6: Vortrag
Mittwoch, 25. März 2009, 16:00–16:15, HSZ 403
Magnetization behaviour of perpendicular magnetized particles and nanostructures — •Matthias Jacobi1, Daniel Stickler1, André Kobs1, Simon Hesse1, Holger Stillrich1, Andreas Frömsdorf2, and 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 investigated the magnetization reversal of submicron Co/Pt structures using anomalous Hall effect (AHE). Two different methods have been used to create the structures from films. The first method is based on highly focused ion beam (FIB), which has been used to pattern the film magnetically. A dose of 5·1014Ga+/cm2 has been applied which destroys ferromagnetism due to intermixing of Co and Pt [1]. Ordered arrays of submicron, ferromagnetic squares are generated. The magnetisation curves obtained by AHE show stepwise reversal, while the homogeneous films exhibit single jump behaviour. The second method is based on the self assembly of diblock-copolymer micelles with silica cores. The cores act as shadow masks during Ar+ sputtering. Hence, arrays of nanometre-sized dots with diameters of about 12 nm and 18 nm are created [2]. In the AHE measurements we can identify the magnetisation curves of the dots although the area filling factor is about 15%. The 12 nm particles show superparamagnetism at room temperature.
[1] P. Warin et al., J. Appl. Phys. 90, 3850 (2001)
[2] H. Stillrich et al., Adv. Funct. Mat. 18, 76 (2008)