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The free energy functional for a spin singlet ferromagnetic superconductor

G. CIOBANU1, F. MOSCALU2,*

Affiliation

  1. University of Bucharest, Romania
  2. ”Ovidius” University, Constanţa, 900527, Romania

Abstract

The aim of this paper is to investigate the coexistence of ferromagnetic and superconducting phase for a system of itinerant fermions using a functional method from the field theory. In this way we present a microscopic derivation of Ginzburg Landau free energy functional for the singlet Cooper pairing system, where the ferromagnetic order appears as a consequence of spontaneously broken spin-rotation symmetry and a contact interaction both for the Heisenberg and the singlet pairing terms was considered. The result is the expanded form of the free functional energy up to 4-th term. Finally we are focusing on the 4-th term of the free energy functional expansion which exhibits both ferromagnetic and superconducting order..

Keywords

Strongly correlated electron systems, GLW free functional, Effective Hamiltonian, Phase transitions.

Submitted at: Oct. 30, 2006
Accepted at: Nov. 2, 2006

Citation

G. CIOBANU, F. MOSCALU, The free energy functional for a spin singlet ferromagnetic superconductor, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 6, pp. 2139-2142 (2006)