Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 19: Micro Magnetism / Computational Magnetism

MA 19.5: Talk

Wednesday, March 25, 2009, 11:15–11:30, HSZ 403

Micromagnetic structure in permalloy rectangles — Holger Stillrich, Sebastian Hankemeier, Nikolai Mikuszeit, Daniel Stickler, Sabine Pütter, Elena Vedmedenko, Robert Frömter, and •Hans Peter Oepen — Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg

Soft magnetic materials like permalloy (Ni₈₀Fe₂₀) are widely used for magnetic nano- and micrometer size elements. The magnetic properties are controlled by the shape of the elements [1]. For rectangular elements with an aspect-ratio of 1:2 two configurations avoiding magnetic poles are found: the Landau and the diamond pattern.

We have studied the micromagnetic structure of 1 µm×2 µm×23 nm elements utilizing a SEM with spin-polarization analysis (SEMPA). An array of well separated elements contains Landau and diamond patterns with equal frequency, as expected from micromagnetic calculations [2]. The histogram of measured magnetization orientations reveals a splitting of the long axis magnetization for Landau structures, while the diamond shows four predominant directions. Analyzing the Landau structure obtained by micromagnetic simulations (OOMMF) reveals similar splitting. In chains of particles with the long edges separated by a gap smaller than particle size magnetostatic coupling occurs and solely Landau patterns are found. The splitting angle increases. A cross-tie wall like domain structure is created across the particles.

[1] A. Hubert and R. Schäfer, Magnetic Domains, (Springer, 1998).

[2] W. Rave and A. Hubert, IEEE Trans. Magn. 36, 3886 (2000). R. Hertel, Zeitschrift für Metallkunde. 93, 957 (2002).