A phenomenological study of superconductivity in rare earth compounds

The effect of critical magnetic scattering is studied in paramagnetic phase of rare earth compounds showing superconductivity and magnetic order. If the exchange coupling between the conduction electrons and the magnetic ions is small the system becomes superconducting between two transition temperatures. The lower one is slightly higher than the magnetic ordering temperature and this is due to the critical magnetic scattering of the conduction electrons. The influence of the lifetime of one electron on the phase transition is briefly discussed.