Evolution of the dynamics of neutral superconductors between BCS and BEC regimes: the variational approach

We use variational approach to analyze the evolution of the dynamics of a neutral s-wave superconductor between BCS and BEC regimes. We consider 2D case, when BCS–BEC crossover occurs already at weak coupling and is governed by the ratio of the two scales — the Fermi energy EF and the bound state en...

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Published in:Физика низких температур
Date:2018
Main Authors: Chubukov, A.V., Mozyrsky, D.
Format: Article
Language:English
Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2018
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Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/176148
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:Evolution of the dynamics of neutral superconductors between BCS and BEC regimes: the variational approach / A.V. Chubukov, D. Mozyrsky // Физика низких температур. — 2018. — Т. 44, № 6. — С. 684-690. — Бібліогр.: 42 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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Summary:We use variational approach to analyze the evolution of the dynamics of a neutral s-wave superconductor between BCS and BEC regimes. We consider 2D case, when BCS–BEC crossover occurs already at weak coupling and is governed by the ratio of the two scales — the Fermi energy EF and the bound state energy for two fermions in a vacuum, E₀. BCS and BEC regimes correspond to EF >> E₀ and EF << E₀, respectively. We compute the spectrum of low-energy bosonic excitations and show that the velocity of phase fluctuations remains υF / √2 through BCS–BEC crossover. We also discuss the topological Aφ ̇ term in the effective action.
ISSN:0132-6414