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Weak Coupling Phases of the Attractive $t-t'$ Hubbard Model at the Van Hove Filling

J. V. Alvarez·J. González
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Abstract

We apply a wilsonian renormalization group approach to the continuum limit of the attractive $t-t'$ 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 $t' = 0.5 t$. 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 $t' = 0.5 t$.

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J. V. Alvarez, J. González. 1998-03-12. Weak Coupling Phases of the Attractive $t-t'$ Hubbard Model at the Van Hove Filling. https://doi.org/10.1209/epl%2Fi1998-00520-y

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