A contractor-renormalization study of Hubbard plaquette clusters

Abstract

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 2-7 smaller than the pairing temperature.

Published version. Extended discussion of CORE and its applicability range. Additional results concerning higher doping levels and the properties of the ground state

References in corpus (7)

• Does Simple Two-Dimensional Hubbard Model Account for High-Tc Superconductivity in Copper Oxides?
• The Optimal Inhomogeneity for Superconductivity: Finite Size Studies
• Numerical Contractor Renormalization Method for Quantum Spin Models
• s-wave Superconductivity Phase Diagram in the Inhomogeneous Two-Dimensional Attractive Hubbard Model
• Suppression of d-wave superconductivity in the checkerboard Hubbard model
• Effect of inhomogeneous coupling on superconductivity
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• Determinant Quantum Monte Carlo Study of d-wave pairing in the Plaquette Hubbard Hamiltonian
• Thermodynamics and magnetism in the 2D-3D crossover of the Hubbard model
• Quantum phase transitions of multi-species Dirac fermions
• d-Wave superconductivity on the checkerboard Hubbard model at weak and strong coupling
• Optimal inhomogeneity for pairing in Hubbard systems with next-nearest-neighbor hopping
• Enhancement of the critical temperature in cuprate superconductors by inhomogeneous doping
• Disorder effects on superconducting tendencies in the checkerboard Hubbard model