Contractor-renormalization study of Hubbard plaquette clusters

Shirit Baruch*, Dror Orgad

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


We implement the contractor-renormalization method to study the checkerboard Hubbard model on various finite-size clusters as function of the inter-plaquette hopping t and the on-site repulsion U at low hole doping. We find that the pair-binding energy and the spin gap exhibit a pronounced maximum at intermediate values of t and U, thus indicating that moderate inhomogeneity of the type considered here substantially enhances the formation of hole pairs. The rise of the pair-binding energy for t < t max ′ is kinetic-energy driven and reflects the strong resonating valence-bond correlations in the ground state that facilitate the motion of bound pairs as compared to single holes. Conversely, as t is increased beyond t max ′ antiferromagnetic magnons proliferate and reduce the potential energy of unpaired holes and with it the pairing strength. For the periodic clusters that we study the estimated phase-ordering temperature at t = t max ′ is a factor of 2-6 smaller than the pairing temperature.

Original languageAmerican English
Article number134537
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number13
StatePublished - 29 Oct 2010


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