Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 18: Magnetic Thin Films II

MA 18.7: Vortrag

Mittwoch, 24. März 2010, 16:45–17:00, H3

Effect of substrate morphology on magnetic anisotropy and domain-structure — •Stefan Rößler, Sebastian Hankemeier, Robert Frömter, and Hans Peter Oepen — Institute of Applied Physics, Hamburg, Germany

In contrast to single crystal silicon substrate, diamond has to be polished to achieve a plain surface. As a result polishing lines remain on the surface of the diamond. The lateral distance of these lines is about 100-200 nm and the height about 1-2 nm, respectively.

We have investigated the impact of these lines on the magnetic properties of a 20 nm Permalloy film. The surface texture of the substrate is replicated in the thin film. The magnetic properties have been investigated by means of magneto optical Kerr effect (MOKE) measurements. These measurements reveal a morphology induced anisotropy with an easy axis of magnetization parallel to the polishing lines.

We have investigated the impact of this anisotropy contribution on the domain structure of 5x5 µ m2 Permalloy squares by means of SEMPA. Due to the high symmetry of these structures they exhibit flux closure domain states, such as the diamond state or the Landau state. The Landau state consists of four triangle shaped domains with magnetizations parallel to the edges of the rectangles curling around a sharp core. It is shown, that the pair of domains with magnetization parallel to the direction of the easy axis are favored and therefore occupy a larger area than the other pair of domains. Thus the straight domain walls of the common Landau state become curved.

This work is supported by DFG via SFB 668.

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