Sublattice model of atomic scale pairing inhomogeneity in a superconductor

Abstract

We study a toy model for a superconductor on a bipartite lattice, where intrinsic pairing inhomogeneity is produced by two different coupling constants on the sublattices. The simplicity of the model allows for analytic solutions and tests of the consequences of atomic-scale variations in pairing interactions which have been considered recently in the cuprates. We present results for the transition temperature, density of states, and thermodynamics of the system over a phase diagram in the plane of two pairing coupling constants. For coupling constants of alternating sign, a gapless superconducting state is stable. Inhomogeneity is generally found to enhance the critical temperature, and at the same time the superfluid density is remarkably robust: at T=0, it is suppressed only in the gapless phase.

arXiv comment9 pages, 11 figures, corrected typo

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• Dynamic cluster quantum Monte Carlo simulations of a two-dimensional Hubbard model with stripe-like charge density wave modulations: Interplay between inhomogeneity and superconductivity
• A contractor-renormalization study of Hubbard plaquette clusters
• Raising the critical temperature by disorder in unconventional superconductors mediated by spin fluctuations
• The quantum compass chain in a transverse magnetic field
• The Low-Temperature Phenomenology of Gap Inhomogeneity in the Cuprate Superconductors: High-Energy Granularity, Low-Energy Homogeneity, and Spectral Kinks