Dresden 2011 – scientific programme

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MA: Fachverband Magnetismus

MA 32: Magnetic Thin Films I

MA 32.6: Talk

Wednesday, March 16, 2011, 12:15–12:30, HSZ 04

Different Methods for the Investigation of a Substrate Induced Uniaxial Anisotropy — •Stefan Rößler, Sebastian Hankemeier, Robert Frömter, and Hans Peter Oepen — Institute of Applied Physics, Hamburg, Germany

As a result of the polishing process polishing lines remain on the surface of a diamond substrate. 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. A model has been developed to evaluate the strength of this anisotropy from the surface configuration. From Atomic Force Microscopy (AFM) analysis we obtain the surface morphology, which is used for the calculation of the uniaxial anisotropy constant. The effect of the anisotropy on the domain pattern in 5 µm × 5 µm × 10 nm Permalloy squares has been investigated by means of SEMPA. From the size of the four domains of a Landau state the local anisotropy in the nanostructure can be calculated utilizing OOMMF simulations. Magnetotransport measurements have been performed with Permalloy squares as a function of the direction of an externally applied magnetic field. The transport results can also be used to determine the strength of the local anisotropy.

This work is supported by DFG via SFB 668.