Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 33: Poster II

MA 33.27: Poster

Friday, March 26, 2010, 11:00–14:00, Poster B1

Ultrafast magnetization dynamics of single antidot structures on nickel — •Darius G. Vahdat-Pajouh, Jakob Walowski, Andreas Mann, Henning Ulrichs, Gerrit Eilers, Benjamin Lenk, and Markus Münzenberg — I. Physikalisches Institut, Universität Göttingen

The time-resolved magnetization dynamics in a thin magnetic film can be investigated with femtosecond laser pulses. After optical excitation (pump pulse) the magnetic relaxation is recorded via the magneto-optical Kerr effect using a second laser pulse of lower intensity (probe pulse) which allows a depiction of M(t).

The aim of this contribution is to find the influence of one single antidot on the magnetization dynamics depending on its diameter and the applied external field. Another point of interest concerns the magnetic mode spectrum and its resemblance to spectra of arrays structures consisting of many periodically arranged antidots. Time resolved magnetization dynamics measurements were performed for various distances from the single circular antidots of different diameters ranging from 5 to 20 micrometers.

The experimental findings indicate that the lower frequency modes generated in the dot vicinity can be accounted to field inhomogeneities arising from dipole surface modes around the structure. These can be predicted by analytical calculations and numerical simulations of the magnetic field in the nickel film.