Weak Coupling Phases of the Attractive $t-t^{\prime }$ Hubbard Model at the Van Hove Filling

Abstract

We apply a wilsonian renormalization group approach to the continuum limit of the attractive $t-t^{\prime }$ Hubbard model, taken when the Fermi level is at the Van Hove singularity of the density of states. The model has well-defined scaling properties and the effective couplings display an unbounded flow in the infrared. We determine the leading instabilities by computing the different response functions up to $t^{\prime }=0.5t$. The phase diagram shows a large boundary between superconducting and charge-density-wave phases, that merge in a triple point with a phase separation instability. The latter is realized down to very low coupling constant, as the Fermi sea degenerates towards a pair of straight lines near $t^{\prime }=0.5t$.

5 pages, 4 figures

References in corpus (1)

• One-Particle Excitation of the Two-Dimensional Hubbard Model

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