Enhanced critical temperature, pairing fluctuation effects, and BCS-BEC crossover in a two-band Fermi gas
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 Nozi\`{e}res-Schmitt-Rink (NSR) 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.
Keywords
Cite
@article{arxiv.1901.11444,
title = {Enhanced critical temperature, pairing fluctuation effects, and BCS-BEC crossover in a two-band Fermi gas},
author = {Hiroyuki Tajima and Yuriy Yerin and Andrea Perali and Pierbiagio Pieri},
journal= {arXiv preprint arXiv:1901.11444},
year = {2019}
}
Comments
7 pages, 6 figures, published version in PRB