Magnetic and pair correlations of the Hubbard model with next-nearest-neighbor hopping
- Departement de Physique and Centre de Recherche en Physique du Solide, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada)
A combination of analytical approaches and quantum Monte Carlo simulations is used to study both magnetic and pairing correlations for a version of the Hubbard model that includes second-neighbor hopping {ital t}{sup {prime}}={minus}0.35{ital t} as a model for high-temperature superconductors. Magnetic properties are analyzed using the two-particle self-consistent approach. The maximum in magnetic susceptibility as a function of doping appears both at finite {ital t}{sup {prime}} and at {ital t}{sup {prime}}=0 but for two totally different physical reasons. When {ital t}{sup {prime}}=0, it is induced by antiferromagnetic correlations while at {ital t}{sup {prime}}={minus}0.35{ital t} it is a band structure effect amplified by interactions. Finally, pairing fluctuations are compared with {ital T}-matrix results to disentangle the effects of van Hove singularity and of nesting on superconducting correlations. The addition of antiferromagnetic fluctuations increases slightly the {ital d}-wave superconducting correlations despite the presence of a van Hove singularity which tends to decrease them in the repulsive model. Some aspects of the phase diagram and some subtleties of finite-size scaling in Monte Carlo simulations, such as inverted finite-size dependence, are also discussed.
- OSTI ID:
- 147787
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 52, Issue 22; Other Information: PBD: 1 Dec 1995
- Country of Publication:
- United States
- Language:
- English
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