Spin-Triplet Pairing Induced by Hund's Rule Exchange in Orbitally Degenerate Systems: Hartree Fock Approximation

We discuss the spin-triplet pairing mechanism induced by the Hund rule ferromagnetic exchange. We include explicitly the e ect of interband hybridization and treat the problem by starting from an extended Hubbard model for a doubly degenerate band, making the simplest Hartree Fock approximation for the part involving the pairing and the Hubbard interaction. The conditions of stability of various phases are determined as a function of both band lling and microscopic parameters. The phase diagram contains regions of stability of the spin-triplet superconducting phase coexisting with either saturated or non-saturated ferromagnetism. Phase diagrams for the cases of constant density of states and that of square lattice have been provided. The in uence of hybridization on the stability of considered phases, as well as the temperature dependences of magnetic moment and the superconducting gap are also discussed.