Coulomb Enhanced Superconducting Pair Correlations in the Frustrated Quarter-Filled Band

Abstract

A necessary condition for superconductivity (SC) driven by electron correlations is that electron-electron (e-e) interactions enhance superconducting pair-pair correlations, relative to the noninteracting limit. We report high-precision numerical calculations of the ground state within the frustrated two-dimensional (2D) Hubbard Hamiltonian for a wide range of carrier concentration $\rho$ (0 < $\rho$ <1) per site. We find that long range superconducting pair correlations are enhanced only for $\rho$ $\simeq$ 0.5. At all other fillings e-e interactions mostly suppress pair correlations. The enhancement of pair correlations is driven by the strong tendency to local singlet bond formation and spin gap (SG) in $\rho$ = 0.5, in lattices with quantum fluctuation. We also report determinantal quantum Monte Carlo (DQMC) calculations that are in strong agreement with our ground state results. Our work provides a key ingredient to the mechanism of SC in the 2D organic charge-transfer solids (CTS), and many other unconventional superconductors with frustrated crystal lattices and $\rho$ $\simeq$ 0.5, while explaining the absence of SC in structurally related materials with substantially different $\rho$.

9 pages, 4 figures; Supplementary information (see ancillary files)

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Cited by in corpus (19)

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• Molecular Quantum Materials: Electronic Phases and Charge Dynamics in Two-Dimensional Organic Solids
• From charge- and spin-ordering to superconductivity in the organic charge-transfer solids
• A DMRG Study of Superconductivity in the Triangular Lattice Hubbard Model
• The Valence Transition Model of Pseudogap, Charge-Order and Superconductivity in Electron- and Hole-Doped Copper Oxides
• Coulomb enhancement of superconducting pair-pair correlations in a $\frac{3}{4}$-filled model for $\kappa$-(BEDT-TTF)${}_2$X
• Charge orders in organic charge-transfer salts
• Ingredients for Generalized Models of $\kappa$-Phase Organic Charge-Transfer Salts: A Review
• Strong light-field effects driven by nearly single-cycle 7-fs light field in correlated organic conductors
• Absence of Luther-Emery Superconducting Phase in the Three-Band Model for Cuprate Ladders
• Cooperative enhancement of superconducting correlations by electron-electron and electron-phonon interactions in the quarter-filled band
• Sr${}_2$RuO${}_4$, like doped cuprates and barium bismuthate, is a negative charge-transfer gap even parity superconductor with $\frac{3}{4}$-filled oxygen band
• Simultaneous Control of Bandfilling and Bandwidth in Electric Double-Layer Transistor Based on Organic Mott Insulator $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]Cl
• Doping asymmetry in the three-band Hamiltonian for cuprate ladders: failure of the standard model of superconductivity in cuprates
• Theory of triangular lattice quasi-one-dimensional charge-transfer solids
• Thermal algebraic-decay charge liquid driven by competing short-range Coulomb repulsion
• Valence Transition Theory of the Pressure-Induced Dimensionality Crossover in Superconducting Sr${}_{14-x}$Ca${}_x$Cu${}_{24}$O${}_{41}$
• Absence of superconductivity in the Hubbard dimer model for kappa-(BEDT-TTF)_2X
• Study of the triangular-lattice Hubbard model with constrained-path quantum Monte Carlo