Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 25: Micro- and Nanostructured Magnetic Materials II

MA 25.8: Talk

Wednesday, March 25, 2009, 16:30–16:45, HSZ 403

The effect of the tapered shape on the magnetostatic anisotropy of magnetic elements — •Sabine Pütter, Nikolai Mikuszeit, Holger Stillrich, Elena Vedmedenko, and Hans Peter Oepen — Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany

Magnetic nano– and microstructures are commonly fabricated by mask techniques. At first glance, the size of the structure depends only on the holes in the mask. However, due to the finite size of the evaporation source and the finite distance of mask and substrate the structure has a certain edge profile. In general, a tapered shape is produced.

In this paper the influence of the tapered shape on the magnetostatic anisotropy is studied for elements with rectangular base. Based on the approach of Rhodes and Rowlands [1] and on straight forward integration of the Poisson equation the demagnetizing energy of uniformly magnetized elements is calculated. We find that the shape anisotropy is drastically reduced due to the modified shape.

When two rectangular elements are aligned parallel to their long axes there is a critical distance at which the easy axis of magnetization switches from the single element’s easy axis to the direction of the connecting line due to the magnetostatic interaction. This distance is increased significantly in case of elements with tapered shape.

The theoretical predictions are compared with the results for micron sized permalloy elements studied by the magneto-optical Kerr effect.

[1] P. Rhodes and G. Rowlands, Proc. Leeds Phil. Liter. Soc. 6 (1954), 191.