Theory of ferromagnetism and superconductivity

Abstract

On the basis of a two-dimensional t– t ′ Hubbard model, the relation between the triplet superconductivity and the ferromagnetism is investigated by the third-order perturbation theory with respect to the on-site Coulomb interaction U. The dominant ferromagnetic superconductivity for the triplet pairing is obtained by the electron–electron correlation between the electron-like majority and hole-like minority bands. In the two bands, both the momentum dependence and the large values of the density of state at Fermi levels are important to the coexistence between the superconductivity and the ferromagnetism.