Quantum-Monte-Carlo Studies of One- and Two-Dimensional Hubbard Models
Despite tremendous efforts, the question of whether two-dimensional repulsive Hubbard-type models have a superconducting phase, i. e. off-diagonal long-range order (ODLRO), is still unresolved. At present there is not even consensus on the symmetry channel in which superconductivity might occur! Therefore we present and numerically analyze two methods to detect superconductivity without any prior knowledge about the nature of the condensate and, in particular, of the symmetry of the underlying pair-pair correlation functions: flux quantization and the temperature derivative of the superfluid density. Both methods rely on generalizations of QMC algorithms to incorporate magnetic fields. Our data confirm the Kosterlitz-Thouless transition in the attractive case and rule out superconductivity in the quarter-filled repulsive one-band Hubbard model.
KeywordsEntropy Depression Eter
Unable to display preview. Download preview PDF.
- 4.For a review, see: E.Y. Loh and J.E. Gubernatis, Stable numerical simulations of models of interacting electrons in condensed-matter physics, in: “Modern Problems in Condensed Matter Sciences”, vol. 32, ed. W. Hanke and Y.V. Kopaev, North Holland (1992).Google Scholar
- 18.F.F. Assaad, W. Hanke and D.J. Scalapino, to appear in Phys. Rev. B. Google Scholar
- 23.R. Preuss et al., Würzburg preprint (1993).Google Scholar