Coexistence of Superconductivity and Ferromagnetism in Intermetallic Uranium-Based Superconductors UCoGe, UIr and UGe2

Abstract

-Starting with a model Hamiltonian for the system with equal spin singlet and triplet pairings based on quantum field theory and green function formalism, we obtain expressions for superconductivity and ferromagnetism parameters. The model exhibits a distinct possibility of the coexistence of superconductivity and ferromagnetism, which are two usually irreconcilable cooperative phenomena, however, recently ferromagnetism and superconductivity have been shown to coexist simultaneously in the newly discovered compounds such as UCoGe, UIr and UGe 2 .The work is motivated by the recent experimental evidences below the superconducting phase temperature in a number of uranium-based superconductors. The theoretical results are then applied to show the coexistence of superconductivity and ferromagnetism in the intermetallic uraniumbased compound UCoGe, UIr and UGe 2 . The limitations of the model are also discussed.