Abstract:
The difference between the free energies of the superconducting
and normal states of a disordered magnetic system in the spin
glass phase is calculated. This difference is expanded with
respect to the order parameter of the superconducting state near
the critical point $T\sim T_{\rm c}$ and a study is made of the behavior
of the expansion coefficients $f_1$ and $f_2$ in the region of
large concentrations of the magnetic impurity, where re-entrant
behavior is observed. It is concluded that at low temperatures the
phase transition to the normal state is a transition of the second
kind, that the solutions of the equation for the critical
temperature of transition of the spin glass to the superconducting
state [2] are physical, and that the superconductivity state in
the spin glass is stable.