A model for coexistent superconductivity and ferromagnetism

Abstract

We explore the various temperature dependences and thermodynamic quantities of a mean-field model of a ferromagnetic–superconducting system. The starting point for this model is based on an s-wave pairing scheme in the singlet channel of the superconducting state and a spontaneously broken-symmetry phase in the ferromagnetic state. We show numerically and analytically that a state of coexistence reveals itself and is favoured energetically over other possible states, and a simple phase diagram is developed. Finally, a comparison of the specific heat with experiment is shown.

Acknowledgements

We gratefully thank J. R. Englebrecht, Y. Joglekar, N. I. Karchev, A. G. Lebed and P. B. Littlewood for useful discussions. This work was done with the support of US Department of Energy grants DEFG0297ER45636 and 60202ER63404.