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MA: Fachverband Magnetismus

MA 33: Poster II

MA 33.71: Poster

Freitag, 26. März 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).