Dresden 2006 – scientific programme

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MA: Magnetismus

MA 18: Spin-Dynamics, Magnetization Reversal I

MA 18.4: Talk

Tuesday, March 28, 2006, 11:00–11:15, HSZ 403

Spatially resolved dynamic eigenmode spectrum of Co rings — •Ingo Neudecker¹, Mathias Kläui², Korbinian Perzlmaier¹, Dirk Backes^2,3, Laura J. Heyderman³, Carlos A. F. Vaz⁴, J. Anthony C. Bland⁴, Ulrich Rüdiger², and Christian H. Back¹ — ¹Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, D-93040 Regensburg, Germany — ²Fachbereich Physik, Universität Konstanz, Universitätsstrasse 10, D-78457 Konstanz, Germany — ³Paul Scherrer Institut, CH-5232 Villingen PSI, Switzerland — ⁴Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 0HE, United Kingdom

We determined the spatially resolved eigenmode spectrum of micrometer-sized Co ring magnets by means of vector network analyzer ferromagnetic resonance combined with time resolved magneto-optic Kerr effect measurements. In doing so up to five resonant eigenmodes were observed in the frequency range from 45 MHz to 20 GHz as a function of an external magnetic bias field. Well defined spatial modes were found both in the vortex and in the onion remanent states. The observed modes correspond to four longitudinal modes, with magnetostatic backward-volume character, and a transverse mode, localized in the transverse domain wall of the onion state. Finally the effect of inter-ring coupling on the modes in the remanent states was investigated. Good agreement between the experimental results and micromagnetic simulations was found. The study demonstrates that the ring representing a high symmetry structure exhibits simple eigenmode behavior.