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MA: Fachverband Magnetismus

MA 23: Micro- and Nanostructured Magnetic Materials I

MA 23.5: Vortrag

Donnerstag, 29. März 2007, 11:15–11:30, H22

Longitudinal Bragg- and Vector-MOKE investigation on the rotational sense of vortices in Permalloy Nanodots — •Min-Sang Lee¹, Andreas Westphalen¹, Arndt Remhof¹, Alexandra Schumann¹, Thorsten Last², Ulrich Kunze², and Hartmut Zabel¹ — ¹Institut für Experimentalphysik IV (Festkörperphysik), Ruhr-Universität Bochum, 44780 Bochum — ²Institut für Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, 44780 Bochum

We have used the Bragg-MOKE technique in longitudinal geometry (L-MOKE) for the first time to study the rotational sense of vortices in Py nanodots. The dots were shaped such that only one uniqely defined rotational sense was present in the whole dot array. Due to the fact that the rotational sense manifests itself in the sign of the imaginary part of magnetic form factors, we have been able to show that the rotational sense can be extracted from the hysteresis loops recorded for positive and negative diffraction order. We have also developed a formalism describing the relation between the magnetic form factor and the Bragg-MOKE signal. This theoretical work has been needed because there is no such formalism regarding the L-MOKE applied to dot arrays. The validity of our formalism is tested by comparsion with the measurement results on the Py dots, which shows a good agreement. We conclude that the L-MOKE is an eligible method for studying the rotational sense of vortices. This work was financially supported by the SFB 491.