Phase diagrams of the two-dimensional one-band t-t8 Hubbard model are obtained within the two-patch and temperature-cutoff many-patch renormalization group approaches. At small t8 and at van Hove band fillings antiferromagnetism dominates, while with increasing t8 or changing filling antiferromagnetism is replaced by d-wave superconductivity. Near t85t/2 and close to van Hove band fillings the ...

We develop series expansions for the ground state properties of the Hubbard model, by introducing an Ising anisotropy into the Hamiltonian. For the two-dimensional (2D) square lattice half-filled Hubbard model, the ground state energy, local moment, sublattice magnetization, uniform magnetic susceptibility and spin stiffness are calculated as a function of U/t, where U is the Coulomb constant a...

We study the structure of symmetric vortices in a Ginzburg–Landau model based on S. C. Zhang’s SO(5) theory of high temperature superconductivity and antiferromagnetism. We consider both a full Ginzburg–Landau theory (with Ginzburg–Landau scaling parameter κ < ∞) and a κ → ∞ limiting model. In all cases we find that the usual superconducting vortices (with normal phase in the central core regio...