Resonant pair-exchange scattering and BCS-BEC crossover in a system composed of dispersive and heavy incipient bands: a Feshbach analogy

Abstract

We theoretically show that a two-band system with very different masses harbors a resonant pair scattering that leads to novel pairing properties, as highlighted by the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensation (BEC) crossover. Most importantly, the interband pair-exchange coupling induces an effective intraband attraction in each band, enhancing the superfluidity/superconductivity. The effect, a kind of Suhl-Kondo mechanism, is specifically enhanced when the second band has a heavy mass and is incipient (lying close to, but just above, the chemical potential, $\mu$), which we call a resonant pair scattering. By elucidating the dependence of the effective interactions and gap functions on $\mu$, we can draw an analogy between the resonant pair scattering and the Feshbach resonance.

11 pages, 8 figures

References in corpus (14)

• Field-induced superconducting phase of FeSe in the BCS-BEC cross-over
• Determination of the Superfluid Gap in Atomic Fermi Gases by Quasiparticle Spectroscopy
• Giant superconducting fluctuations in the compensated semimetal FeSe at the BCS-BEC crossover
• Goldstone mode and pair-breaking excitations in atomic Fermi superfluids
• Fermion Superfluids of Non-Zero Orbital Angular Momentum near Resonance
• Observation of strong electron pairing on bands without Fermi surfaces in LiFe1-xCoxAs
• Band-edge BCS-BEC crossover in a two-band superconductor: physical properties and detection parameters
• Two-band superfluidity from the BCS to the BEC limit
• Enhanced critical temperature, pairing fluctuation effects, and BCS-BEC crossover in a two-band Fermi gas
• Enhancing Kondo Coupling in Alkaline-Earth Atomic Gases with Confinement-induced Resonances in Mixed Dimensions
• Resonant multigap superconductivity at room temperature near a Lifshitz topological transition in sulfur hydrides
• Trapped ${}^{173}$Yb Fermi gas across an orbital Feshbach resonance
• Room temperature superconductivity dome at a Fano resonance in superlattices of wires
• Two-band description of resonant superfluidity in atomic Fermi gases

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• High-Tc superconducting dome in artificial heterostructures made of nanoscale quantum building blocks
• Superconductivity enhanced by pair fluctuations between wide and narrow bands
• Upper critical magnetic field and multiband superconductivity in artificial high-Tc superlattices of nano quantum wells
• Emergent Fano-Feshbach resonance in two-band superconductors with an incipient quasi-flat band: Enhanced critical temperature evading particle-hole fluctuations
• Flat bands in condensed-matter systems -- perspective for magnetism and superconductivity
• Inversion symmetry breaking in bilayer multi-orbital Hubbard model with impurity approximation
• BCS-BCS crossover between atomic and molecular superfluids in a Bose-Fermi mixture
• High magnetic field response of superconductivity dome in quantum artificial High Tc superlattices with variable geometry