Abstract

Second sound is a quantum mechanical effect manifesting itself as a wave-like (in contrast with diffusion) heat transfer, or energy propagation, in a gas of quasi-particles. So far, this phenomenon has been observed only in an equilibrium gas of phonons existing in liquid/solid helium, or in dielectric crystals (Bi, NaF) at low temperatures. Here, we report observation of a room-temperature magnonic second sound, or a wave-like transport of both energy and spin angular momentum, in a quasi-equilibrium gas of magnons undergoing Bose-Einstein condensation (BEC) in a ferrite film. Due to the contact of the magnon gas with pumping photons and phonons, dispersion of the magnonic second sound differ qualitatively from the phononic case, as there is no diffusion regime, and the second sound velocity remains finite at low wavenumbers. Formation of BEC in the gas of magnons modifies the second sound properties by creating an additional channel of energy relaxation.

Details

Title
Excitation of coherent second sound waves in a dense magnon gas
Author
Tiberkevich, V 1 ; Borisenko, I V 2 ; Nowik-Boltyk, P 3 ; Demidov, V E 3 ; Rinkevich, A B 4 ; Demokritov, S O 5 ; Slavin, A N 1 

 Department of Physics, OaklandUniversity, Rochester, MI, USA 
 Departmentof Physics and Center for Nonlinear Science, University of Muenster, Muenster, Germany; Kotel’nikov Institute of Radio Engineering and Electronics, RussianAcademy of Sciences, Moscow, Russia 
 Departmentof Physics and Center for Nonlinear Science, University of Muenster, Muenster, Germany 
 Institute of Metal Physics, Ural Division of RAS, Ekaterinburg, Russia 
 Departmentof Physics and Center for Nonlinear Science, University of Muenster, Muenster, Germany; Institute of Metal Physics, Ural Division of RAS, Ekaterinburg, Russia 
Pages
1-9
Publication year
2019
Publication date
Jun 2019
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2244646975
Copyright
© 2019. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.