Problemi evolutivi per le equazioni di Ginzburg-Landau e invarianza di gauge

                           Prof. Mauro Fabrizio

                         (Universitą di Bologna)

 

The aim of the presentation is addressed to the study of the Ginzburg-Landau 
theory that yields the behaviour of a superconductor near to the phase 
transition. We show that the pertinent equations can be derived starting from 
the representation of the free energy in terms of the magnetic field H instead 
of the vector potential A, such that rot A=µ H and the modulus |F| which 
denotes the concentration of superconducting electrons, instead of the complex 
parameter F Such a representation gives also a conceptual simplification of the
model since it makes use of observable quantities. In addition, the free energy
in terms of H and |F| makes the theory gauge-invariant in that is free from the
vector potential A and the phase of |F|. The compatibility with thermodynamics 
is examined and it follows that the generality of the second law is related to 
the specific approximation of the model.