COEXISTENCE OF SUPERCONDUCTIVITY AND FERROMAGNETISM IN UGe2

We investigate the coexistence of ferromagnetism and superconductivity in UGe 2 and Sr 2 RuO 4 in analogy with our previous model3 for high transition temperature superconductivity (HTSC). The Coulomb interaction for triplet electron pairs is reduced by a difference of the exchange interaction. If the electron–electron interaction Usf for UGe 2 and Usd for Sr 2 RuO 4 are larger than the reduced Coulomb interaction, superconductivity must happen. Under the same conditions, the coexistence of superconductivity and ferromagnetism is impossible in the case of our scheme, but changing phonons by pressures makes the coexistence possible for UGe 2.