Abstract
We study signatures of superconductivity in a two-leg “checkerboard” Hubbard ladder model, defined as a one-dimensional (period 2) array of square plaquettes with an intraplaquette hopping and interplaquette hopping , using the density-matrix renormalization-group method. The highest pairing scale (characterized by the spin gap or the pair binding energy, extrapolated to the thermodynamic limit) is found for doping levels close to half-filling, and . Other forms of modulated hopping parameters, with periods of either one or three lattice constants, are also found to enhance pairing relative to the uniform two-leg ladder, although to a lesser degree. A calculation of the phase stiffness of the ladder reveals that in the regime with the strongest pairing, the energy scale associated with phase ordering is comparable to the pairing scale.
3 More- Received 23 August 2010
DOI:https://doi.org/10.1103/PhysRevB.83.054508
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