Signature of pressure-induced phase separation in Ce1−xLaxRu2 system

The Ce1−xLaxRu2 system has been studied for its superconducting and normal-state properties by high-pressure ac-susceptibility measurements as a function of temperature in the range of 4.3–300 K using a cubic anvil pressure cell. The CeRu2 compound shows a sharp transition at the Tc that becomes wider with increasing pressure, getting as wide as ∼1.8 K at a pressure of 7.5 GPa. The transition for the Ce0.91La0.09Ru2 appears with a width of ∼0.7 K (about 3 times wider than that for the CeRu2 at 0.5 GPa) and gets wider with increasing pressure, similar to the case of the CeRu2 system. The pressure-dependent broadening and anomalous Tc behavior of the Ce1−xLaxRu2 could be related to the Fermi surface topological instability that drives the system to get phase separated in the superconducting and weakly antiferromagnetic domains.