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 t'=-0.35t 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 t' and at t'=0 but for two totally different physical reasons. When t'=0, it is induced by antiferromagnetic correlations while at t'=-0.35t it is a band structure effect amplified by interactions. Finally, pairing fluctuations are compared with 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 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.

%B Physical Review B %V 52 %P 16255–16263 %G eng %0 Conference Proceedings %B Superconducting Symposium 1994 %D 1994 %T Quantum Monte Carlo simulations for a model of high-tem¬perature superconductors: effect of next-nearest-neighbor hopping %A Veilleux, A. F. %A Daré, A.-M. %A Chen, L. %A Vilk, Y.M. %A A.-M. S. Tremblay %E John W. Ross %B Superconducting Symposium 1994 %V University of Toronto Press %P 78-85 %8 1994