Regensburg 2004 – scientific programme

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MA: Magnetismus

MA 28: Spindynamik / Ummagnetisierungsvorg
änge

MA 28.5: Talk

Thursday, March 11, 2004, 16:15–16:30, H23

Spin Dynamics in Permalloy Disks with Vortex Structure — •Matthias Buess^1,2, Rainer Höllinger¹, Thomas Haug¹, Korbinian Perzlmaier¹, Michael R. Scheinfein³, Danilo Pescia², and Christian H. Back¹ — ¹Institut fürExperimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany — ²Laboratorium für Festkörperphysik,Eidgenössische Technische Hochschule Zürich, CH-8093Zürich,Switzerland — ³Simon Fraser University, 8888 University Drive, Burnaby BC U5A 156, Canada

Micron sized ferromagnetic permalloy disks exhibiting a ferromagnetic vortex structure are excited by a magnetic field pulse. The fast rise time pulse field is generated by an optically triggered electrical pulse in a lithographically fabricated microcoil. The excitation is imaged using time resolved magneto-optic polar Kerr microscopy - a stroboscopic experiment. We present the spatially resolved magnetic maps at different delay times, stitched together to form a magnetic movie. The dynamical excitations are composed of symmetric and non-sysmmetric parts which can not be separated at first glance. However, in the Fourier transformation of the magnetic movie we identify several modes which can be accounted for in a simple model based on purely dipolar interactions. The model is supported by micromagnetic simulations and shows good quantitative agreement in the resonance frequencies for different modes and sample dimensions.