Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 64: Poster 1
MA 64.59: Poster
Freitag, 24. März 2017, 09:30–13:00, P2-EG
Magnon Supercurrents by Thermal Gradients — •Alexander J.E. Kreil1, Dmytro A. Bozhko1,2, Alexander A. Serga1, and Burkard Hillebrands1 — 1Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany — 2Graduate School Materials Science in Mainz, Germany
Currently, supercurrents in a room-temperature magnon Bose-Einstein condensate (BEC) have been reported [1]. The condensate created by parametric microwave pumping in a tangentially magnetized yttrium-iron-garnet (YIG) film is studied by means of the time-resolved Brillouin light scattering (BLS) spectroscopy technique. The heating in the focus of a probing laser beam leads to the temperature-induced spatial variation in the saturation magnetization and, thus, to the variation in the local magnon frequencies across the heated film area. Because the magnon condensate is coherent across the entire heated area, a spatially varying phase shift is imprinted into its wavefunction. This spatial phase gradient propels a magnon supercurrent flowing out the the probing point. The evidence of these supercurrents was obtained by an observation of the different relaxation behaviors of the magnon BEC at different heating times.
Now, by adding an external heat source, namely a second laser, we are able to perform spatial-resolved measurements and are therefore able to study the transport properties of the magnon supercurrents. We present here the measured data of the performed experiment.
[1] Bozhko et al. Nature Physics 12, 1057 (2016)