Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 19: Spin Dynamics / Spin Torque I

MA 19.16: Vortrag

Mittwoch, 27. Februar 2008, 18:00–18:15, EB 301

Dynamic Properties of Patterned Ferromagnetic Thin Films — •Roman Adam, Riccardo Hertel, and Claus M. Schneider — Institute of Solid State Research, Research Center Jülich, D-52425 Jülich, Germany

We studied dynamic response of ferromagnetic thin film bars to magnetic pulse excitations employing both time-resolved magneto-optic Kerr effect (TR-MOKE) measurements and micromagnetic simulations. The bars with rectangular and hexagonal geometries were patterned on top of coplanar waveguides and oriented with their long axis either parallel, perpendicular or 45° with respect to the external magnetic field. The bars were inserted into weak magnetic field and excited with 10 ps magnetic pulse generated by a photoconducting switch. The time evolution of the magnetization was recorded employing TR-MOKE and compared with micromagnetic simulations. Fourier analysis of the time-resolved signal reveals the presence of oscillatory modes associated with the dynamics in the central part and at the borders of ferromagnetic bars. The observed initial gradual increase of the oscillation amplitude is attributed to the excitation of multiple modes inside the sampled region. A strongly nonlinear dependence of the relaxation time on the static field suggests an even more complex response due to mode interactions.