Impurity effects on BCS-BEC crossover in ultracold atomic Fermi gases

Abstract

We present a systematic investigation of the effects of "nonmagnetic" impurities on the $s$-wave BCS-BEC crossover in atomic Fermi gases within a pairing fluctuation theory. Both pairing and impurity scattering $T$-matrices are treated self-consistently at the same time. While the system is less sensitive to impurity scattering in the Born limit, for strong impurity scatterers, both the frequency and the gap function are highly renormalized, leading to significant suppression of the superfluid $T_c$, the order parameter and the superfluid density. We also find the formation of impurity bands and smearing of coherence peak in the fermion density of states, leading to a spectrum weight transfer and finite lifetime of Bogoliubov quasiparticles. In the BCS regime, the superfluidity may be readily destroyed by the impurity of high density. In comparison, the superfluidity in unitary and BEC regimes is relatively more robust.

arXiv comment9 pages, 9 figures

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Cited by in corpus (4)

• When Superconductivity Crosses Over: From BCS to BEC
• The Gor'kov and Melik-Barkhudarov correction to an imbalanced Fermi gas in the presence of impurities
• The Gor'kov and Melik-Barkhudarov correction to the mean-field critical field transition to Fulde-Ferrell-Larkin-Ovchinnikov states
• Self-consistent inclusion of disorder in the BCS-BEC crossover near the critical temperature