Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 18: Poster I : Bio Magn. (1-2); Mag.Imgaging (3-9); Magn. Semiconductors (10-16); Half Metals & Oxides (17-20); Coupl.Phenomena (21-27); Magn. Mat. (28-41); Micro & Nanostr. Magn. Materials (42-61); Micro Magn. (62-64); Surface Magnetism (65-70); Transport Phenomena (71-85)

MA 18.62: Poster

Tuesday, February 26, 2008, 15:15–18:30, Poster E

Simulation of the magnetization dynamics of ferromagnetic layers on nano-spheres — •Daniel Mutter and Peter Nielaba — Physics Department, University of Konstanz, 78457 Konstanz, Germany

In this work we investigated the magnetization-dynamics of ferromagnetic caps on nano-spheres with computer simulations. These caps are regarded as a promising approach for a further reduction of the magnetic storage density in hard-disks [1]. In our calculations, the magnetic volume was modeled by magnetic moments, arranged on a discrete lattice, which interact with each other due to exchange and dipole-dipole coupling [2]. Additionally, there is an anisotropy in the system, which is directed perpendicular to the surface of the sphere. The dynamics was analyzed by numerical solving of a stochastic extension of the Landau-Lifshitz-Gilbert equation to include temperature effects. We present results concerning hysteresis-effects for different cap- and cell-sizes in the presence of external magnetic fields under various angles. The dynamics of the magnetization reversal at the coercive field strength is analyzed, and a comparison with the behavior of classical Stoner-Wohlfahrt particles shows significant differences in the reversal mechanisms.

[1] M. Albrecht, G. Hu et al., Magnetic multilayers on nanospheres, Nature Materials, 4, 203 (2005).

[2] U. Nowak, Thermally activated reversal in magnetic nanostructures, Annual Reviews of Computational Physics, IX, 105-151 (2001).