Superconducting and normal properties of CeCu2Ge2 at high pressure

The electronic properties of CeCu2Ge2 have been investigated under pressure (P) up to 25 GPa by detailed resistivity versus temperature (50 mK < T < 300 K) measurements performed in the basal plane of the tetragonal structure for different single crystals. With increasing P, the compound evolves from antiferromagnetically ordered Kondo to intermediate valence behaviour as the Kondo temperature increases by about two orders of magnitude. At low P, two magnetic ordering temperatures are observed. Magnetic ordering vanishes between 7 and 10 GPa, depending on the sample, and in parallel, superconductivity appears at a critical temperature Tc ∝ 0.6 K which remains nearly constant up to 13 GPa. At higher P, Tc increases rapidly, reaches almost 2 K for P ∝ 16 GPa and then vanishes at P ∝ 20 GPa. The Tc(P) maximum corresponds to the occurrence of a pronounced maximum of the residual resistivity. (orig.)