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MA: Fachverband Magnetismus

MA 10: Magnetization Dynamics I

MA 10.2: Vortrag

Montag, 14. März 2011, 15:00–15:15, HSZ 403

Interference of two magnon-Bose-Einstein-condensates in real space — •Patryk Nowik- Boltyk, Oleksandr Dzyapko, Vladislav Demidov, and Sergej O. Demokritov — Institute of Applied Physics, University of Münster, 48149 Münster, Germany

Since the discovery of Bose-Einstein condensation (BEC) of microwave-driven magnons in ferrite films [1] at room temperature several indirect demonstrations of the time and spatial coherence of the magnon-condensate have been published [2,3,4]. However, the most direct confirmation of the coherence is the interference of two condensates. The main distinction of magnon BEC from other BEC-systems is that it takes place at a quantum state with a non-zero wavevector, k. Due to the obvious symmetry of the system two condensates at +k and -k are simultaneously created in the same region of the real space.

Here we present the observation of the spatial inference of two condensates corresponding to +k and -k. To keep the coherence during the time of the measurement, the magnon gas was driven by microwaves continuously and two dimensional spatial interference patterns of the total condensate density in real space were mapped using the Brillouin light scattering spectroscopy. The wavevector of the condensate obtained from the spatial period of the patterns matches very well with the data of previous measurements in the phase space [4].

[1]Demokritov et al., Nature 443, 430 (2006)

[2]Demokritov et al., New Journal of Physics 10, 045029 (2008)

[3]Dzyapko et al., Appl. Phys. Lett. 92, 162510 (2008)

[4]Demidov et al., Phys. Rev. Lett. 101, 257201 (2008)