Pressure Studies near Quantum Phase Transitions in Strongly Correlated Ce Systems.

Abstract

Non-Fermi-liquid (NFL) effects in the temperature dependences of both the resistivity and specific heat have been investigated at hydrostatic tatic static pressures p≤1. 7GPa and magnetic fields B≤8T for "A-type" CeCu2Si2, some of its disordered derivatives and its homologue CeNi2Ge2. In dilute (La, Ce) Cu2. 2. Si2, the NFL phenomena hint at a quantum critical point of spin-glass type. In CeCu2Si2, NFL effects show up at the breakdown of phase A. However, the data cannot be explained consistently by the properties of a "nearly antiferromagnetic Fermi liquid". The origin of the NFL effects in CeNi2Ge2 is yet unclear. For this compound, a novel phase transition at T1=0. 9 K (p=1. 7GPa) and an incipient superconducting transition below T=0. 1 K (p=0) in a very clean sample are discovered.