Low Temperature Physics: 41, 801 (2015); https://doi.org/10.1063/1.4932354
Fizika Nizkikh Temperatur: Volume 41, Number 10 (October 2015), p. 1024-1029    ( to contents , go back )

Formation of Bose–Einstein magnon condensate via dipolar and exchange thermalization channels

D.A. Bozhko1,2, P. Clausen1, A.V. Chumak1, Yu.V. Kobljanskyj3,B. Hillebrands1, and A.A. Serga1

1Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern 67663, Germany

2Graduate School Materials Science in Mainz, 47 Gottlieb-Daimler-Straße, Kaiserslautern 67663, Germany
E-mail: bozhko@physik.uni-kl.de

3Faculty of Radiophysics, Electronics and Computer Systems, Taras Shevchenko National University of Kyiv Kyiv 01601, Ukraine

Received April 17, 2015

Abstract

Thermalization of a parametrically driven magnon gas leading to the formation of a Bose–Einstein condensate at the bottom of a spin-wave spectrum was studied by time- and wavevector-resolved Brillouin light scattering spectroscopy. Two distinct channels of the thermalization process related on dipolar and exchange parts of a magnon gas spectrum are clearly determined. It has been found that the magnon population in these thermalization channels strongly depends on applied microwave pumping power. The observed magnon redistribution between the channels is caused by the downward frequency shift of the magnon gas spectrum due to the decrease of the saturation magnetization in the course of injection of parametrically pumped magnons.

PACS: 05.30.Jp Boson systems;
PACS: 75.30.Ds Spin waves;
PACS: 75.70.–i Magnetic properties of thin films, surfaces, and interfaces.

Key words: magnon, thermalization, Bose–Einstein condensate.

Published online: August 25, 2015

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