QUANTUM-PHASE TRANSITIONS IN CEPD2SI2 AND CERH2SI2

We compare the cross-over from a magnetically ordered to a non-magneti c spin liquid state as a function of hydrostatic pressure in the relat ed heavy-fermion antiferromagnets CePd2Si2 and CeRh2Si2. Both material s exhibit superconductivity at pressures close to the critical pressur e p(c) at which their magnetic ordering temperatures extrapolate to ze ro. However, in CePd2Si2 the normal state resistivity varies according to rho similar to T-x (1.1 < x < 1.3) near p(c), while CeRh2Si2 retur ns to the Fermi-liquid form rho similar to T-2. This discrepancy betwe en the two materials may be connected to the rapid destruction of the magnetic state in CeRh,Si, with hydrostatic pressure.