Superconductivity enhanced by pair fluctuations between wide and narrow bands

Abstract

Full or empty narrow bands near the Fermi level are known to enhance superconductivity by promoting scattering processes and spin fluctuations. Here, we demonstrate that doublon-holon fluctuations in systems with half-filled narrow bands can similarly boost the superconducting $T_c$. We study the half-filled attractive bilayer Hubbard model on the square lattice using dynamical mean-field theory. The band structure of the noninteracting system contains a wide band formed by bonding orbitals and a narrow band formed by antibonding orbitals, with bandwidths tunable by the inter-layer hopping. The shrinking of the narrow band can lead to a substantial increase in the superconducting order parameter and phase stiffness in the wide band. At the same time, the coupling to the wide band allows the narrow band to remain superconducting -- and to reach the largest order parameter -- in the flat band limit. We develop an anomalous worm sampling method to study superconductivity in the limit of vanishing effective hopping. By analyzing the histogram of the local eigenstates, we clarify how the interplay between different interaction terms in the bonding/antibonding basis promotes pair fluctuations and superconductivity.

arXiv comment7+12 pages, 4+7 figures

References in corpus (53)

• Magic-angle graphene superlattices: a new platform for unconventional superconductivity
• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• Superconductivity in Iron Compounds
• Continuous-time Monte Carlo methods for quantum impurity models
• Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3
• A continuous-time solver for quantum impurity models
• Magic continuum in twisted bilayer WSe2
• The superconductivity at 18 K in LiFeAs system
• Phase Diagram and High Temperature Superconductivity at 65 K in Tuning Carrier Concentration of Single-Layer FeSe Films
• Superconductivity up to 37 K in (A1-xSrx)Fe2As2 with A=K and Cs
• Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films
• Electric Field Tunable Correlated States and Magnetic Phase Transitions in Twisted Bilayer-Bilayer Graphene
• Superfluidity in topologically nontrivial flat bands
• Orbital Fluctuation Mediated Superconductivity in Iron Pnictides: Analysis of Five Orbital Hubbard-Holstein Model
• Spin-polarized Correlated Insulator and Superconductor in Twisted Double Bilayer Graphene
• Electronic Origin of High Temperature Superconductivity in Single-Layer FeSe Superconductor
• Correlated states in twisted double bilayer graphene
• Hybridization expansion impurity solver: General formulation and application to Kondo lattice and two-orbital models
• Superconductivity and the Pseudogap in the two-dimensional Hubbard model
• Direct observation of high temperature superconductivity in one-unit-cell FeSe films
• Monolayer FeSe on SrTiO${}_3$
• The Synthesis and Characterization of LiFeAs and NaFeAs
• Superconducting gap anisotropy in monolayer FeSe thin film
• Direct observation of particle-hole mixing in the superconducting state by angle-resolved photoemission
• Superconductivity from emerging magnetic moments
• What makes the Tc of monolayer FeSe on SrTiO3 so high: a sign-problem-free quantum Monte Carlo study
• Electron pairing in the presence of incipient bands in iron-based superconductors
• Theoretical possibilities for flat-band superconductivity
• Superconductivity in repulsively interacting fermions on a diamond chain: flat-band induced pairing
• Optical Spectral Weight, Phase Stiffness and Tc Bounds for Trivial and Topological Flat Band Superconductors
• $i$QIST: An open source continuous-time quantum Monte Carlo impurity solver toolkit
• High Tc via spin fluctuations from incipient bands: application to monolayers and intercalates of FeSe
• High T_c superconductivity due to coexisting wide and narrow bands: A fluctuation exchange study on the Hubbard ladder as a test case
• Worm Improved Estimators in Continuous-time Quantum Monte Carlo
• Spontaneous orbital-selective Mott transitions and the Jahn-Teller metal of A${}_3$C${}_{60}$
• Continuous-time Quantum Monte Carlo using Worm Sampling
• A spin-freezing perspective on cuprates
• Negative sign problem in continuous-time quantum Monte Carlo: optimal choice of single-particle basis for impurity problems
• Superconductivity and Nematic Fluctuations in a model of FeSe monolayers: A Determinant Quantum Monte Carlo Study
• $i$QIST v0.7: An open source continuous-time quantum Monte Carlo impurity solver toolkit
• Maximum Entropy Analytic Continuation for Spectral Functions with Non-Positive Spectral Weight
• Long-range orders, spin- and orbital-freezing in the two-band Hubbard model
• Strongly enhanced superconductivity due to finite energy spin fluctuations induced by an incipient band : a FLEX study on the bilayer Hubbard model with vertical and diagonal interlayer hoppings
• Superfluid state of repulsively interacting three-component fermionic atoms in optical lattices
• Ergodicity of the Hybridization-Expansion Monte Carlo Algorithm for Broken-Symmetry States
• Superfluid stiffness in cuprates: Effect of Mott transition and phase competition
• Many-variable variational Monte-Carlo study of superconductivity in two-band Hubbard models with an incipient band
• Resonant pair-exchange scattering and BCS-BEC crossover in a system composed of dispersive and heavy incipient bands: a Feshbach analogy
• Unconventional Pairing from Local Orbital Fluctuations in Strongly Correlated A${}_3$C${}_{60}$
• Ferromagnetic spin correlations in the two-dimensional Hubbard model
• Pairing enhanced by local orbital fluctuations in a model for monolayer FeSe
• Entropy and specific heat of the infinite-dimensional three-orbital Hubbard model

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• High-$T_c$ Berezinskii-Kosterlitz-Thouless transition in 2D superconducting systems with coupled deep and quasi-flat electronic bands with van Hove singularities
• Emergent Fano-Feshbach resonance in two-band superconductors with an incipient quasi-flat band: Enhanced critical temperature evading particle-hole fluctuations
• Maximum entropy analytic continuation of anomalous self-energies
• Flat bands in condensed-matter systems -- perspective for magnetism and superconductivity
• Spin correlations in the bilayer Hubbard model with perpendicular electric field
• Bypassing the lattice BCS-BEC crossover in strongly correlated superconductors: resilient coherence from multiorbital physics
• Inversion symmetry breaking in bilayer multi-orbital Hubbard model with impurity approximation
• Instability of Pa$\overline{3}$ Cs${}_3$C${}_{60}$ at ambient pressure and superconducting state of the FCC phase