General conditions for coexisting itinerant ferromagnetism and singlet superconductivity

We consider the problem of the coexistence of metallic ferromagnetism and singlet superconductivity assuming that the magnetic instability is due to asymmetric spin dependent effective mass. The phase diagram and the evolution of the order parameters at zero temperature is obtained as a function of the spin split mass and the average kinetic energy by analyzing the case of dressing and undressing of the effective mass in the coexisting and ferromagnetic phase with respect to the unpolarized superconducting state. (c) 2005 Elsevier Ltd. All rights reserved.