Hofstadter-Hubbard model with opposite magnetic fields: Bardeen-Cooper-Schrieffer pairing and superfluidity in the nearly flat butterfly bands

Abstract

Despite the multi-band spectrum of the widely-known Hofstadter butterfly, it turns out that the pairing correlations of the time-reversal-symmetric Hofstadter-Hubbard model are well-described by a single order parameter that is uniform in real space. By exploiting a BCS mean-field theory for the nearly-flat butterfly-bands regime of low magnetic-flux limit, here we reveal a number of unusual superfluid properties both in the ground state and at finite temperatures. Our thorough analysis includes but is not limited to the order parameter, condensate and superfluid fractions, and the critical BCS and BKT transition temperatures.

7 pages with 1 figure; to appear in PRA

References in corpus (4)

• Band geometry, Berry curvature and superfluid weight
• Time-Reversal-Invariant Hofstadter-Hubbard Model with Ultracold Fermions
• Perturbative Approach to Flat Chern Bands in the Hofstadter Model
• Quantum phases of Fermi-Fermi mixtures in optical lattices

Cited by in corpus (5)

• Origin of flat-band superfluidity on the Mielke checkerboard lattice
• Extracting quantum-geometric effects from Ginzburg-Landau theory in a multiband Hubbard model
• Cooper pairing, flat-band superconductivity and quantum geometry in the pyrochlore-Hubbard model
• Berezinskii-Kosterlitz-Thouless transition in the time-reversal-symmetric Hofstadter-Hubbard model
• Superconductivity in a Topological Lattice Model with Strong Repulsion