On the relationship of magnetism and superconductivity in materials containing partially filled f shells

We discuss the low-temperature normal-state properties of the prototypical heavy-fermion (HF) superconductor CeCu2Si2 as well as their variations as a function of stoichiometry, applied pressure and magnetic field. Related re sults on the homologous compound CeNi2Ge2 are also presented. In contrast t o CeCu2Si2 where HF superconductivity can survive in the presence of high r esidual resistivities (rho(0) less than or equal to 40 mu Omega cm), the ne wly discovered HF superconducting state in CeNi2Ge2 requires rho(0) < 1.5 m u Omega cm. Our results point to striking disparities between resistivity a nd specific-heat results in both compounds. These observations raise doubts as to the applicability of the "nearly-antiferromagnetic-Fermi-liquid" the ory to HF compounds.