Pressure studies of quantum critical effects in CeCu2Si2 and CeNi2Ge2

We have investigated the effect of pressure and magnetic field on the specific heat of CeCu2Si2 and CeNi2Ge2, two undoped compounds close to an antiferromagnetic (afm) quantum critical point. In a CeCu2Si2 sample showing an afm phase at p = 0, application of a pressure of p = 0.7 GPa results in a replacement of this phase by superconductivity and to non-Fermi-liquid (NFL) behaviour in C/T. In CeNi2Ge2 the NFL behaviour present at p = 0 is suppressed by either a magnetic field B = 8 T or a pressure p = 1.3 GPa. For both compounds, the NFL effects are consistent (as T --> 0) with C/T = gamma(0) - alpha T-1/2 as expected when T-N --> 0.