Reliability of the ginzburg-landau theory in the bcs-bec crossover by including gaussian fluctuations for 3d attractive fermions

Year: 2021

Authors: Pascucci F.; Perali A.; Salasnich L.

Autors Affiliation: Univ Camerino, Sch Sci & Technol, Phys Div, Via Madonna Carceri 9B, I-62032 Camerino, Italy; Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy; Univ Camerino, Sch Pharm, Phys Unit, Via Madonna Carceri 9B, I-62032 Camerino, Italy; Unita Sesto Fiorentino, INO CNR, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Italy; INFN, Sez Padova, Via Marzolo 8, I-35131 Padua, Italy.

Abstract: We calculate the parameters of the Ginzburg-Landau (GL) equation of a three-dimensional attractive Fermi gas around the superfluid critical temperature. We compare different levels of approximation throughout the Bardeen-Cooper-Schrieffer (BCS) to the Bose-Einstein Condensate (BEC) regime. We show that the inclusion of Gaussian fluctuations strongly modifies the values of the Ginzburg-Landau parameters approaching the BEC regime of the crossover. We investigate the reliability of the Ginzburg-Landau theory, with fluctuations, studying the behavior of the coherence length and of the critical rotational frequencies throughout the BCS-BEC crossover. The effect of the Gaussian fluctuations gives qualitative correct trends of the considered physical quantities from the BCS regime up to the unitary limit of the BCS-BEC crossover. Approaching the BEC regime, the Ginzburg-Landau equation with the inclusion of Gaussian fluctuations turns out to be unreliable.

Journal/Review: CONDENSED MATTER

Volume: 6 (4)      Pages from: 49-1  to: 49-12

KeyWords: Ginzburg-Landau theory; BCS-BEC crossover; pair fluctuations
DOI: 10.3390/condmat6040049

Citations: 2
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