PRESSURE EFFECTS IN CE AND YB-BASED HF COMPOUNDS

From high-pressure resistivity measurements of CeAu2Si2, CeCu2Ge2, CeC u2 and YbCu2Si2 we discuss the key role of the volume for electronic c ouplings of heavy fermions and namely the competition between RKKY and Kondo couplings. The superconducting transition temperature of CeCu2G e2 climbs up to T-c approximate to 1.8K at 15.6GPa. At this pressure t he residual scattering is maximum and the resistivity follows a linear temperature dependence up to about 15K.