Weak-coupling phases of the attractive Hubbard model at the Van Hove filling
Departamento de Matemáticas, Universidad Carlos III Butarque 15, Leganés, 28913 Madrid, Spain
2 Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas Serrano 123, 28006 Madrid, Spain
Accepted: 8 October 1998
We apply a Wilsonian renormalization group approach to the continuum limit of the attractive Hubbard model, taken when the Fermi level is at the Van Hove singularity of the density of states. We determine the leading instabilities by computing the different response functions up to . 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 .
PACS: 71.27.+a – Strongly correlated electron systems; heavy fermions / 74.20.Mn – Nonconventional mechanisms (spin fluctuations, polarons and bipolarons, resonating valence bond model, anyon mechanism, marginal Fermi liquid, Luttinger liquid, etc.)
© EDP Sciences, 1998