  In the heavy-fermion materials CeCoIn$_5$ and UBe$_{13}$, the superconducting
order parameter is coupled to flucutating magnetization of the uncompensated
part of the localized $f$-moments. We find that this coupling decreases the
superconducting transition temperature and increases the jump of the
specific-heat coefficient, which indicates entropy transfer from the magnetic
to the superconducting degree of freedom at the transition temperature. Below
the transition, we find that the magnetic fluctuations are suppressed. We
discuss the relation of our results to experiments on CeCoIn$_5$ under
pressure.
