Effects of van Hove singularities on magnetism and superconductivity in the t-t ' Hubbard model: A parquet approach - art. no. 165107

The t-t' Hubbard model for the Fermi level near the van Hove singularity is considered within the renormalization group and parquet approaches. Interp lay of ferromagnetic, antiferromagnetic, and superconducting channels is in vestigated, and the phase diagram of the model is constructed. In compariso n with previous approaches, the account of ferromagnetic fluctuations suppr esses superconducting pairing and, vice versa, the influence of the Cooper channel decreases the Curie temperature, so that the Stoner criterion is in applicable even qualitatively.