2008/03/31 by Wei-Feng Tsai, Hong Yao, Andreas Laeuchli +2
Physics and Astronomy · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.77.214502
published as Phys. Rev. B 77, 214502 (2008) · 8 pages, 9 figures; minor revisions; more references added
openalex publication_date 2008/06/04 · arxiv created 2008/06/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We report the results of exact-diagonalization studies of Hubbard models on a 4\ifmmode×\else\texttimes\fi4 square lattice with periodic boundary conditions and various degrees and patterns of inhomogeneity, which are represented by inequivalent hopping integrals t and t^\ensuremath'. We focus primarily on two patterns, the checkerboard and the striped cases, for a large range of values of the on-site repulsion U and doped hole concentration x. We present evidence that superconductivity is strongest for U of the order of the bandwidth and intermediate inhomogeneity 0<t^\ensuremath'<t. The maximum value of the ``pair-binding energy'' we have found with purely repulsive interactions is \ensuremathΔpb=0.32t for the checkerboard Hubbard model with U=8t and t^\ensuremath'=0.5t. Moreover, for near-optimal values, our results are insensitive to changes in boundary conditions, suggesting that the correlation length is sufficiently short that finite-size effects are already unimportant.