The Gor'kov and Melik‐Barkhudarov Correction to the Mean‐Field Critical Field Transition to Fulde–Ferrell–Larkin–Ovchinnikov States

Abstract

The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states, characterized by Cooper pairs condensed at finite-momentum are, at the same time, exotic and elusive. It is partially due to the fact that the FFLO states allow superconductivity to survive even in strong magnetic fields at the mean-field level. The effects of induced interactions at zero temperature are calculated in both clean and dirty cases, and it is found that the critical field at which the quantum phase transition to an FFLO state occurs at the mean-field level is strongly suppressed in imbalanced Fermi gases. This strongly shrinks the phase space region where the FFLO state is unstable and more exotic ground state is to be found. In the presence of high level impurities, this shrinkage may destroy the FFLO state completely.

The Gor'kov and Melik-Barkhudarov correction to an imbalanced Fermi gas in the presence of impurities

“…Considering the screening of the interaction, ρ turns out to be dependent on L. As we have seen previously (see Fig. 3), this function varies from the maximum value obtained in the balanced situation L(y = 0) = 0.795 to its lower value, which is for the fully polarized case L(y = 1, γ = 0) = 0.69 [72]. Considering the "polaronic limit" as that of L(y = 1, γ = 0), we get ρ ≈ 0.46.…”

“…[58] and references therein). Besides, the GMB correction shrinks the MF FFLO window, making it even more difficult to be unambiguously observed, at least in 3D [72]. The tricritical point at the end of the MF second-order curve at (yc, Tc) ≈ (0.63, 0.37) is also shown.…”

The Gor'kov and Melik‐Barkhudarov Correction to an Imbalanced Fermi Gas in the Presence of Impurities

“…[73] Considering the screening of the interaction, 𝜌 turns out to be dependent on L. As we have seen previously (see Figure 3), this function varies from the maximum value obtained in the balanced situation L(y = 0) = 0.795 to its lower value, which is for the fully polarized case L(y = 1, γ = 0) = 0.69. [72] Considering the "polaronic limit" as that of L(y = 1, γ = 0), we get 𝜌 ≈ 0.46.…”

“…Besides, the GMB correction shrinks the MF FFLO window, making it even more difficult to be unambiguously observed, at least in 3D. [72]…”