Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 30: Spin-Dynamics / Spin-Torque III

MA 30.10: Talk

Thursday, March 26, 2009, 12:30–12:45, HSZ 04

Lifetime of quantized spin waves in nano-scaled magnetic ring structures — •Helmut Schultheiß, Björn Obry, Christian Sandweg, Sebastian Hermsdörfer, Sebastian Schäfer, Thomas Sebastian, Britta Leven, and Burkard Hillebrands — Fachbereich Physik and Research Center OPTIMAS, TU Kaiserslautern, 67663 Kaiserslautern, Germany

The magnetization dynamics of rings, magnetized in the onion state, shows a rich eigenmode spectrum. Quantization of spin waves takes place not only due to the spatial confinement in radial and azimuthal directions, but also in spin-wave wells in the so-called pole regions created by the inhomogeneity of the internal magnetic field. To understand the dissipation mechanisms and coupling between different spin-wave modes, we have investigated the relaxation processes using time- and space-resolved Brillouin light scattering microscopy. The decay of the magnetization after excitation with a short microwave pulse was studied as a function of frequency and position. We have determined the decay constants of the spin-wave modes that can be excited with in-plane microwave pulses. The comparison of the dissipation times of the ring eigenmodes confined in the pole and equatorial regions, respectively, of the onion state indicates that different dissipation mechanisms are responsible for the relaxation of the magnetization, depending on the position and the quantization conditions of the spin-wave eigenmodes. Financial support by the DFG (SPP1133) is acknowledged.