A Supercondutividade e o Formalismo de Nambu

Abstract

In this paper we presented a study of the superconducting phase transition, which outlines the thermodynamics involved in a description of the mean field (order parameter). The Ginzburg-Landau model uses an order-parameter-dependent functional to describe the thermodynamic phase transition involving. The free energy function given in terms of this parameter provides the essential elements to extract the behavior of entropy, specific heat, and the number of superelectrons. However, this model does not explain how the pair of electrons can overcome the Coulomb repulsion energy and stabilize. Using the formalism of Nambu it is possible to expose how this occurs. On the other hand, the superconducting ceramics (eg, Hg, Re-1223, studied at the Group of Applied Physics UFES) consist of grains that form an interpenetrating set Josephson microjunction (the "weak-link"). Thus one can use the concepts in this type of join to present the microscopic physical processes involved in high-temperature superconductors. Finally, in this thesis one describes the formation of this type of joint.