Influence of induced interactions on superfluid properties of quasi-two-dimensional dilute Fermi gases with spin-orbit coupling

Abstract

We study the effects of induced interactions on the pairing gap, transition temperature, and chemical potential of a quasi-two-dimensional Fermi gas of atoms with spin-orbit coupling. We find that these mean-field parameters are significantly modified when induced interactions are taken into account. We also investigate the implications of induced interaction corrections for the BEC-BCS crossover driven by spin-orbit coupling, which happens even for small (compared to the Fermi energy) values of the binding energy.

Induced interactions in the BCS-BEC crossover of two-dimensional Fermi gases with Rashba spin-orbit coupling

“…Our formulation of the induced interaction extends the previous approach [66] where only the interbranch χ ⇑⇓ was considered within diagram 1. Later, we will show that the contribution of χ ⇑⇓ is rather small at strong SOC.…”

“…In two-component Fermi gases with attractive s-wave interaction, without SOC, the screening effect of the induced interaction reduces critical temperature, for instance, by a ratio of about 2.22 in three dimensions [54,55] and about 2.72 in two dimensions [56,57]. The GM correction has been also extended to systems with mass imbalance [58], optical lattices [59], BEC-BCS crossover [60], spin-density polarization [61], threecomponent gases [62], polar molecules [63][64][65], and spinorbit coupling [66,67].…”

“…Second, the mixed-spin-state character of the Fermi sea abruptly changes across the SOCdriven BCS-BEC crossover [31], which may substantially affect the medium contributions to the induced interaction. However, these properties are not included in the earlier consideration of the induced interaction for a spinorbit-coupled system [66].…”

Comment on “Influence of induced interactions on superfluid properties of quasi-two-dimensional dilute Fermi gases with spin-orbit coupling”

“…The accurate estimation of superfluid transition temperature is of clear importance in ultracold gas systems where the realization of the SOC becomes possible in a controllable environment (for instance, see [2]). In [1], they obtained the analytical expressions of the induced interaction in the weak and strong SOC regimes, claiming that (i) the magnitude of the induced interaction is exactly the same as the value for the case without SOC in the weak coupling regime, and (ii) in the strong SOC regime, the magnitude starts from a reduced value but recovers the zero-SOC case in the limit of large SOC. Unfortunately, these claims are flawed because of the critical errors and physical inconsistencies found in their calculations.…”

“…We point out that their calculations contain the critical errors and inconsistencies that significantly affect the basis of these claims. Caldas et al [1] calculated the induced interaction for attractively interacting Fermi gases with Rashba spin-orbit coupling (SOC) in two dimensions. They provided the first calculation considering the Gorkov-Melik-Barkhudarov (GMB) correction to the superfluid properties in presence of the Rashba SOC.…”