Pairing and superconductivity in the flat band: Creutz lattice

Abstract : We use unbiased numerical methods to study the onset of pair superfluidity in a system that displays flat bands in the noninteracting regime. This is achieved by using a known example of flat band systems, namely the Creutz lattice, where we investigate the role of local attractive interactions in the $U < 0$ Hubbard model. Going beyond the standard approach used in these systems where weak interactions are considered, we map the superfluid behavior for a wide range of interaction strengths and exhibit a crossover between BCS and tightly bound bosonic fermion pairs. We further contrast these results with a standard two-leg fermionic ladder, showing that the pair correlations, although displaying algebraic decay in both cases, are longer ranged in the Creutz lattice, signifying the robustness of pairing in this system.
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Contributor : Benoît Grémaud <>
Submitted on : Tuesday, February 26, 2019 - 4:26:28 PM
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Benoît Grémaud, Rubem Mondaini, G. George Batrouni. Pairing and superconductivity in the flat band: Creutz lattice. Physical Review B : Condensed matter and materials physics, American Physical Society, 2018, 98 (15), pp.155142. ⟨10.1103/PhysRevB.98.155142⟩. ⟨hal-02049814⟩



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