Enhancement effect of mass imbalance on Fulde-Ferrell-Larkin-Ovchinnikov type of pairing in Fermi-Fermi mixtures of ultracold quantum gases

Wang, Jibiao; Che, Yanming; Zhang, L.; Chen, Qijin

doi:10.1038/srep39783

Cited by 37 publications

(31 citation statements)

References 67 publications

(111 reference statements)

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“…The population imbalance is defined as η = δn/n. The FFLO wavevector q can be determined via ∂χ(0,p) ∂p | p=q = 0, which is equivalent to minimizing the thermodynamic potential Ω S with respect to q [22]. Then we have…”

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confidence: 99%

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Instability of Fulde-Ferrell-Larkin-Ovchinnikov states in atomic Fermi gases in three and two dimensions

et al. 2018

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The exotic Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states have been actively searched for experimentally since the mean-field based FFLO theories were put forward half a century ago. Here we investigate the stability of FFLO states against unavoidable pairing fluctuations, and conclude that FFLO superfluids cannot exist due to their intrinsic instability in three and two dimensions. This explains their absence in experimental observations in both condensed matter systems and the most recent, more promising ultracold atomic Fermi gases with a population imbalance.

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confidence: 99%

“…The counterpart phase diagrams for Fermi-Fermi mixtures such as 6 Li-40 K can be found in Ref. [22].…”

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Instability of Fulde-Ferrell-Larkin-Ovchinnikov states in atomic Fermi gases in three and two dimensions

et al. 2018

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“…In the context of ultracold two-component Fermi gases some exotic phases like the paradigmatic Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) [10][11][12], Sarma [13] as well as interior [14] and exterior gap breached-pair phases [15], have been theorized. Specifically the FFLO phase seems to be experimentally achievable in mass-imbalanced systems at unitarity, because of the higher superfluid transition temperature [16][17][18][19] relative to the equalmass case. In general the mass-imbalanced stronglyinteracting fermionic mixtures based on cold atoms, as a result of the generated Fermi surfaces and single particle dispersion mismatch, exhibit a rich phase diagram, which includes a Lifshitz point and population dependent asymmetry [20][21][22][23].…”

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Production of a degenerate Fermi-Fermi mixture of dysprosium and potassium atoms

et al. 2018

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We report on the realization of a mixture of fermionic 161 Dy and fermionic 40 K where both species are deep in the quantum-degenerate regime. Both components are spin-polarized in their absolute ground states, and the low temperatures are achieved by means of evaporative cooling of the dipolar dysprosium atoms together with sympathetic cooling of the potassium atoms. We describe the trapping and cooling methods, in particular the final evaporation stage, which leads to Fermi degeneracy of both species. Analyzing cross-species thermalization we obtain an estimate of the magnitude of the inter-species s-wave scattering length at low magnetic field. We demonstrate magnetic levitation of the mixture as a tool to ensure spatial overlap of the two components. The properties of the Dy-K mixture make it a very promising candidate to explore the physics of strongly interacting mass-imbalanced Fermi-Fermi mixtures. arXiv:1810.13437v1 [cond-mat.quant-gas]

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“…For instance, some calculations indicate that if a FFLO phase exists in 3D trapped gases, it will occupy a very small volume in parameter space [32][33][34]. Another kind of pairing and phase coherence that can appear is the spatially homogeneous spin-polarized superfluidity (called breached pair state or Sarma phase [35]), which has a gapless spectrum for the majority spin species.…”

Section: Introductionmentioning

confidence: 99%

Critical behavior in one dimension: Unconventional pairing, phase separation, BEC-BCS crossover, and magnetic Lifshitz transition

et al. 2017

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We study the superconducting properties of population-imbalanced ultracold Fermi mixtures in one-dimensional (1D) optical lattices that can be effectively described by the spin-imbalanced attractive Hubbard model (AHM) in the presence of a Zeeman magnetic field. We use the mean-field theory approach to obtain the ground state phase diagrams including some unconventional superconducting phases such as the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase, and the η phase (an extremal case of the FFLO phase), both for the case of a fixed chemical potential and for a fixed number of particles. It allows to determine optimal regimes for the FFLO phase as well as η-pairing stability. We also investigate the evolution from the weak coupling (BCS-like limit) to the strong coupling limit of tightly bound local pairs (BEC) with increasing attraction, at T = 0. Finally, the obtained results show that despite of the occurrence of the Lifshitz transition induced by an external magnetic field, the superconducting state can still exist in the system, at higher magnetic field values.

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Enhancement effect of mass imbalance on Fulde-Ferrell-Larkin-Ovchinnikov type of pairing in Fermi-Fermi mixtures of ultracold quantum gases

Cited by 37 publications

References 67 publications

Instability of Fulde-Ferrell-Larkin-Ovchinnikov states in atomic Fermi gases in three and two dimensions

Instability of Fulde-Ferrell-Larkin-Ovchinnikov states in atomic Fermi gases in three and two dimensions

Production of a degenerate Fermi-Fermi mixture of dysprosium and potassium atoms

Critical behavior in one dimension: Unconventional pairing, phase separation, BEC-BCS crossover, and magnetic Lifshitz transition

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