Supercondutores ferromagnéticos no modelo de Ginzburg-Landau

Abstract

We introduce the modi ed Ginzburg-Landau theory by means of a superconducting order parameter with two components and a magnetic order parameter with three components, as this allows the analysis of phase diagrams in the superconducting and ferromagnetic states. We also discuss the basic theories presented by some scholars who have attempted to explain the conductivity and, above all, superconductivity that have served as a basis in the studies of other works, such as the case of the treatment of electronic conduction behaving in the same way as a particulate gas, superconducting state to be treated as a two-uid model. We discuss in the rst chapter an introduction with a brief historical summary, from the discovery of the electron until when the superconductivity was known with cooling of materials, because the null resistance and the expulsion of the external magnetic elds are characterized, but the superconducting state is an intrinsic property of the material. We veri ed the theories of London, Ginzburg-landau and BCS that are related to the superconductivity and shown in the second chapter, in which we verify studies of microscopic and macroscopic phenomena, besides the classi cation of types I and II of this state of matter. A study on the coexistence of the ferromagnetic and superconducting phases is veri ed by means of spontaneous magnetization, starting from the normalized free energy density, presented in the third chapter. But we verify the phenomenology of GL with two order parameters in order to perform the behavior of some solutions of energy disunity by means of programming resources with the use of Mathematica and graphical analysis of the phase domains.