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MA: Magnetismus
MA 18: Spin-Dynamics, Magnetization Reversal I
MA 18.5: Vortrag
Dienstag, 28. März 2006, 11:15–11:30, HSZ 403
Correlation of ferromagnetic precessional modes and domain wall density in patterned ferromagnetic films — •Ute Queitsch1, Jeffrey McCord1, Rudolf Schäfer1, Ludwig Schultz1, Karsten Rott2, and Hubert Brückl2 — 1Leibniz Institut für Festkörper- und Werkstoffforschung (IFW), Helmholtzstrasse 20, 01069 Dresden — 2Universität Bielefeld, Lehrstuhl für Dünne Schichten und Nanostrukturen, Universitätsstrasse 25, 33615 Bielefeld
Understanding the correlation between magnetic microstructure and hf-response of patterned soft magnetic thin films is crucial for hf applications. The hf response of arrays of CoZrTa single and bi-layer thin film elements (200µ m×50µ m×80nm) was investigated by means of pulsed inductive microwave magnetometry and directly compared to the domain structure analyzed by time resolved wide field Kerr microscopy. Different domain states were preset by varying the magnetic field history. Characteristic changes in the hf response depending on the domain wall density were observed. Domain walls were found to have a lower permeability compared to freely rotatable regions, leading to an additional contribution to the acting anisotropy field which leads to a drastic rise in the dominating ferromagnetic resonance frequency of the film. The demagnetizing field of the 90∘-closure domain walls causes different modes of excitation and relaxation. Domain wall movements during the dynamic remagnetization process cause frequency components in the 100 MHz range. Due to stray field coupling the bilayers show an irregular domain pattern without closure domains which leads to a strong reduction of the number of precessional modes and domain wall movements.