Regensburg 2010 – scientific programme
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MA: Fachverband Magnetismus
MA 33: Poster II
MA 33.71: Poster
Friday, March 26, 2010, 11:00–14:00, Poster B1
Interaction of two magnon condensates — •Vitaliy I. Vasyuchka1, Alexander A. Serga1, Christian W. Sandweg1, Andrii V. Chumak1, Timo Neumann1, Björn Obry1, Helmut Schultheiss1, Gennadiy A. Melkov2, Andrei N. Slavin3, and Burkard Hillebrands1 — 1FB Physik and Landesforschungszentrum OPTIMAS, TU Kaiserslautern, 67663 Kaiserslautern, Germany — 2Department of Radiophysics, National Taras Shevchenko University of Kiev, Ukraine — 3Department of Physics, Oakland University, Rochester, MI, USA
The interaction of two magnon condensates was studied by means of time-resolved Brillouin light scattering spectroscopy in a tangentially magnetized yttrium-iron-garnet film at room temperature. Both condensates were created using parametric microwave pumping. Firstly, the pump action results in the injection of phase correlated magnon pairs at half of the pumping frequency. Thus a condensate of photon coupled magnons arises. Secondly, a Bose-Einstein condensate (BEC) of magnons is formed at the lowest energy state [1]. We show that the interaction of these two condensates leads to distortion of the BEC of magnons due to scattering on the condensate of magnon pairs. Shortly after the pumping is switched off this distortion vanishes and the BEC signal increases drastically. Applying a second probing pump pulse during the pump-free evolution of the BEC of magnons results in the restoration of the condensate of magnon pairs and consequently in a sharp slump of the BEC signal. Financial support by the DFG (SFB/TRR 49). [1] S.O. Demokritov et al., Nature 443, 430 (2006).