Teoria di Ginzburg-Landau per superconduttori di tipo I e II

In the first chapter of this work it is presented a phenomenology of superconductivity in metals, the properties of those metals are then analized with a simple theoretical model: the Lonond equation. The second chapter introduces the main charateristics of the Ginzburg-Landau theory, such as the order parameter and the Ginzburg-Landau functional. First we discuss spatially uniform systems, then spatially varying systems and finally systems in an external magnetic field. For all of these systems we use the Ginzburg-Landau functional to find an equation for the order parameter and, in the last case, for the magnetic field. In the end we study the superficial energy of the transition region between normal and superconducting state to show how important this quantity is the classification of superconductors in type I or II.