Abstract
Spin-polarized attractive Fermi gases in one-dimensional (1D) optical lattices are expected to be remarkably good candidates for the observation of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. We model these systems with an attractive Hubbard model with population imbalance. By means of the density-matrix renormalization-group method, we compute the pairing correlations as well as the static spin and charge structure factors in the whole range from weak to strong coupling. We demonstrate that pairing correlations exhibit quasi-long-range order and oscillations at the wave number expected from the FFLO theory. However, we also show by numerically computing the mixed spin-charge static structure factor that charge and spin degrees of freedom appear to be coupled already for a small imbalance. We discuss the consequences of this coupling for the observation of the FFLO phase, as well as for the stabilization of the quasi-long-range order into long-range order by coupling many identical 1D systems, such as in quasi-1D optical lattices.
Highlights
Multicomponent attractive fermionic systems with unequal masses, densities, or chemical potentials have attracted continued interest for many decades in several fields of physics ranging from high-energy[1,2] to condensed matter[2,3] and, more recently, atomic physics.[4,5,6] The interplay between pairing and density imbalance of the different fermion species leads to a rich scenario, which includes the possibility of various exotic superconducting states.[7]
We show by numerically computing the mixed spin-charge static structure factor that charge and spin degrees of freedom appear to be coupled already for a small imbalance
We discuss the consequences of this coupling for the observation of the FFLO phase, as well as for the stabilization of the quasi-long-range order into long-range order by coupling many identical 1D systems, such as in quasi-1D optical lattices
Summary
Multicomponent attractive fermionic systems with unequal masses, densities, or chemical potentials have attracted continued interest for many decades in several fields of physics ranging from high-energy[1,2] to condensed matter[2,3] and, more recently, atomic physics.[4,5,6] The interplay between pairing and density imbalance of the different fermion species leads to a rich scenario, which includes the possibility of various exotic superconducting states.[7]. The most favorable systems for the observation of the FFLO phase were predicted to be clean superconducting films in the presence of an in-planei.e., Zeemanmagnetic field, which is above the so-called Clogston-Chandrasekhar limit.[9] despite the fact that the original prediction dates back to more than 30 years ago, the FFLO phase has been very elusive to detect
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