Possibility of coexistence of ferromagnetism and superconductivity in an anisotropic quasi-two-dimensional system

Possibility of coexistence of ferromagnetism (FM) and superconductivity (SC) in UGe2 based on a two-parameter model in an anisotropic quasi-two-dimensional system is discussed with both singlet s-wave and triplet p-wave SCs. It is emphasized that the coexistence of FM and singlet s-wave SC is energetically high among all possible states, while the coexistence of FM and triplet p-wave SC is energetically favourable among all possible states. Furthermore, we End that the magnetization dependence of the SC energy gap is nonmonotonic, which may explain the experimental result discovered in UGe2.