We study the superfluid critical temperature in a two-band attractive Fermi system with strong pairing fluctuations associated with both interband and intraband couplings. We focus specifically on a configuration where the intraband coupling is varied from weak to strong in a shallow band coupled to a weakly interacting deeper band. The whole crossover from the Bardeen-Cooper-Schrieffer (BCS) condensation of largely overlapping Cooper pairs to the Bose-Einstein condensation (BEC) of tightly bound molecules is covered by our analysis, which is based on the extension of the Nozieres-Schmitt-Rink approach to a two-band system. In comparison with the single-band case, we find a strong enhancement of the critical temperature, a significant reduction of the preformed pair region where pseudogap effects are expected, and the entanglement of two kinds of composite bosons in the strong-coupling BEC regime.

Tajima H., YERIN, Y., Perali A., Pieri P. (2019). Enhanced critical temperature, pairing fluctuation effects, and BCS-BEC crossover in a two-band Fermi gas. PHYSICAL REVIEW. B, 99(18), 1-6 [10.1103/PhysRevB.99.180503].

Enhanced critical temperature, pairing fluctuation effects, and BCS-BEC crossover in a two-band Fermi gas

Pieri P.
2019

Abstract

We study the superfluid critical temperature in a two-band attractive Fermi system with strong pairing fluctuations associated with both interband and intraband couplings. We focus specifically on a configuration where the intraband coupling is varied from weak to strong in a shallow band coupled to a weakly interacting deeper band. The whole crossover from the Bardeen-Cooper-Schrieffer (BCS) condensation of largely overlapping Cooper pairs to the Bose-Einstein condensation (BEC) of tightly bound molecules is covered by our analysis, which is based on the extension of the Nozieres-Schmitt-Rink approach to a two-band system. In comparison with the single-band case, we find a strong enhancement of the critical temperature, a significant reduction of the preformed pair region where pseudogap effects are expected, and the entanglement of two kinds of composite bosons in the strong-coupling BEC regime.
2019
Tajima H., YERIN, Y., Perali A., Pieri P. (2019). Enhanced critical temperature, pairing fluctuation effects, and BCS-BEC crossover in a two-band Fermi gas. PHYSICAL REVIEW. B, 99(18), 1-6 [10.1103/PhysRevB.99.180503].
Tajima H.; YERIN, YURIY; Perali A.; Pieri P.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/771230
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