Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 27: Spin currents and spin torques

MA 27.5: Vortrag

Mittwoch, 14. März 2018, 10:30–10:45, EB 407

Long-distance supercurrent transport in a magnon Bose-Einstein condensate — •Alexander J.E. Kreil, Dmytro A. Bozhko, Alexander A. Serga, and Burkard Hillebrands — Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany

Currently, supercurrents in a room-temperature magnon Bose-Einstein condensate (BEC) have been reported [1]. The condensate is created by parametric microwave pumping in a tangentially magnetized yttrium-iron-garnet (YIG) film. We study the condensate by means of time-resolved Brillouin light scattering spectroscopy (BLS). By heating the sample, a spatially variation of the saturation magnetization is induced, which leads to a change of the magnon frequencies across the heated film. Because the magnon condensate is coherent across the entire heated area, a spatial varying phase shift is imprinted into its wavefunction. The spatial phase gradient generates a magnon supercurrent flowing out of the probing point. The earlier evidence of these supercurrents was obtained by an observation of the different relaxation behaviors of the magnon BEC under different heating conditions. By heating the sample with an external heat source, we are able to perform spatially resolved measurements. In this work we are showing the one-dimensional supercurrent transport measured over a large distance whereby travelling magnon density wave packets could be observed.

[1] Bozhko et al. Nature Physics 12, 1057 (2016)