Bose-Einstein Condensation of Magnons and Spin Superfluidity in the Polar Phase of
Phys Rev Lett
; 121(2): 025303, 2018 Jul 13.
Article
em En
| MEDLINE
| ID: mdl-30085748
ABSTRACT
The polar phase of ^{3}He, which is topological spin-triplet superfluid with the Dirac nodal line in the spectrum of Bogoliubov quasiparticles, has been recently stabilized in a nanoconfined geometry. We pump magnetic excitations (magnons) into the sample of polar phase and observe how they form a Bose-Einstein condensate, revealed by coherent precession of the magnetization of the sample. Spin superfluidity, which supports this coherence, is associated with the spontaneous breaking of U(1) symmetry by the phase of precession. We observe the corresponding Nambu-Goldstone boson and measure its mass emerging when applied rf field violates the U(1) symmetry explicitly. We suggest that the magnon BEC in the polar phase is a powerful probe for topological objects such as vortices and solitons and topological nodes in the fermionic spectrum.
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01-internacional
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MEDLINE
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article