Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 55: Poster II
MA 55.30: Poster
Freitag, 4. April 2014, 10:30–13:30, P2
Bose-Einstein condensation of exchange magnons — •Peter Clausen1, Dmytro A. Bozhko1, Vitaliy I. Vasyuchka1, Alexander A. Serga1, Gennadii A. Melkov2, and Burkard Hillebrands1 — 1Fachbereich Physik and Landesforschungszentrum OPTIMAS, TU Kaiserslautern, Germany — 2Faculty of Radiophysics, Taras Shevchenko National University of Kyiv, Ukraine
The technique of parallel parametric pumping is widely used to inject magnons in ferri- and ferromagnetic films. However, the physics of the evolution of a parametrically pumped magnon gas is still under investigation. We report on this evolution by four-magnon scattering of a non-equilibrium magnon gas in time and wavevector space.
The measurements were performed using a combined microwave and Brillouin light scattering (BLS) setup.
We find two groups of magnons at different positions in time and wavevector space. We identify them with the parametrically pumped magnons and the magnon Bose-Einstein-condensate at the bottom of the magnon spectrum. However, there is a 25 ns long gap between those two magnon groups where no BLS signal is observed.
Our model shows, that this gap in the BLS signal can be explained solely by multi-stage four-magnon scattering from energy minima to minima of high longitudinal BVMSW thickness mode mainly outside of the wavevector detection window of (0−12)·104 rad/cm from the experimental setup.
Support by the DFG within the SFB/TRR 49 is gratefully acknowledged.