Estudo fenomenológico dos supercondutores ferromagnéticos

Abstract

This work presents a study of the phase diagram of a ferromagnetic superconductors. The presence of a magnetic phase in the structure of these materials is what differentiates it from the conventional superconductors. The explanation for this coexistence between superconductivity and magnetism relies on the 5f electrons, which is responsable for both phenomenon. Starting from a free energy functional that describes the energy system and its relation to the external quantities (magnetic field, applied currents, impurities and defects). We introduce an order parameter with two complex components in the description of free energy. Forward with the components of magnetization, a description of the magnetic superconductor behavior requires a determination of six variables. Thus, the equivalent of the first Ginzburg-Landau equation for conventional superconductors is a system with six equations in the ferromagnetic superconductors. In this context, we study numerically the phase diagram built from the solutions of the system of equations, where we identify purely superconducting, purely magnetic phases and the conditions for a magnetic phase to coexist with a superconductor.