Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 19: Spin-Dynamics/Switching I
MA 19.11: Talk
Wednesday, March 28, 2007, 17:45–18:00, H23
Brillouin light scattering observations of a magnetodielectric wave in thin ferrite films — •Timo Neumann1, Natalia Sergeeva1,2, Thomas Schneider1, Alexander Serga1, and Burkard Hillebrands1 — 1TU Kaiserslautern, Kaiserslautern, Germany — 2Elektrotechnical University, St. Petersburg, Russia
We report on optical observations of a thermally excited mode detected above the region of existence of dipolar dominated spin waves in thin, in-plane magnetized YIG-films. The possibility to amplify this mode by means of longitudinal parametrical pumping is demonstrated.
In experiments with 7 µm thick YIG-films in a tangentially applied, static magnetic bias field, a thermally excited mode was observed for field strength H0 varying from below 100 Oe to 4300 Oe using the Brillouin light scattering spectroscopy technique. A linear dependence of the mode frequency ω, which lies above the frequency of Damon-Eshbach modes, on the external magnetic field was found.
Effective parametric amplification was realized in the case when the pumping frequency ωP equalled approximately twice the frequency ω of the mode. In contrast, no significant amplification of the signal was noted for other ratios 2 > ωP / ω > 0,7 considered. In particular, direct perpendicular force excitation with ωP = ω, as can be easily achieved for magnetic modes, did not take place.
We associate the observed thermal mode to a magnetodielectric wave localized in the sample.
Financial support by the MATCOR "Graduate Class of Excellence", GRK 792, and DAAD Grant 6205-A0556601 is recognized gratefully.