Pressure–temperature phase diagram of CeAg

Abstract We have performed electrical-resistivity measurements under hydrostatic pressures ranging up to 4.47 GPa on the cubic compound CeAg. A pressure–temperature phase diagram has been revised in a high-pressure range above ∼ 2.1 GPa , where the system is known to enter into an unidentified phase through a first-order phase transition. We have found that the electrical resistivity shows a clear kink anomaly below ∼ 4 K in this unknown phase. The anomaly shifts to lower temperature with increasing pressure, and shows a tendency to reach absolute zero at ∼ 6 GPa , suggesting the presence of a pressure-induced quantum critical point around this pressure. We have also observed that a first-order phase boundary line, which separates the phase diagram into two regions of a tetragonal phase and the unidentified phase, seems to terminate in a critical end point located at ( P CEP , T CEP ) ∼ ( 3.2 GPa , 200 K ) . This suggests that the crystal symmetry of the unidentified phase above ∼ 2.1 GPa is also tetragonal.