Eur. Phys. J. B (2013) 86: 463
https://doi.org/10.1140/epjb/e2013-40172-6

Regular Article

Dynamics of a Bose-Einstein condensate of excited magnons

Condensed Matter Physics Department, Institute of Physics “Gleb Wataghin”, State University of Campinas - UNICAMP, 13083-859 Campinas, SP, Brazil

^a e-mail: fabiosv@ifi.unicamp.br
^b Deceased on 13 October 2012
^c Group Home Page: www.ifi.unicamp.br/~aurea

Received: 1 March 2013
Received in final form: 20 August 2013
Published online: 7 November 2013

Abstract

The emergence of a non-equilibrium Bose-Einstein-like condensation of magnons in rf-pumped magnetic thin films has recently been experimentally observed. We present here a complete theoretical description of the non-equilibrium processes involved. It is demonstrated that the phenomenon is another example of the presence of a Bose-Einstein-like condensation in non-equilibrium many-boson systems embedded in a thermal bath, better referred-to as Fröhlich-Bose-Einstein condensation. The complex behavior emerges after a threshold of the exciting intensity is attained. It is inhibited at higher intensities when the magnon-magnon interaction drives the magnons to internal thermalization. The observed behavior of the relaxation to equilibrium after the end of the pumping pulse is also accounted for and the different processes fully described.