Quantum-phase transitions in CePd2Si2 and CeRh2Si2

We compare the cross-over from a magnetically ordered to a non-magnetic spin liquid state as a function of hydrostatic pressure in the related heavy-fermion antiferromagnets CePd2Si2 and CeRh2Si2. Both materials exhibit superconductivity at pressures close to the critical pressure p(c) at which their magnetic ordering temperatures extrapolate to zero. 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 returns to the Fermi-liquid form rho similar to T-2. This discrepancy between the two materials may be connected to the rapid destruction of the magnetic state in CeRh,Si, with hydrostatic pressure.