Pressure Effect on Yb-Based Strongly Correlated Electron Systems

We studied pressure effects on YbCu5 and YbInCu4, good examples of the Yb-based compounds to investigate the nonmagnetic-magnetic transition in Yb-based strongly correlated electron systems.With increasing pressure, the low-temperature Fermi liquid state of YbCu5 is gradually suppressed, suggesting the second-order like nonmagnetic-magnetic transition around the pressure of 5-6 GPa.On the other hand, in YbInCu4 which has a pressure-induced magnetic ordered ground state above PC = 2.45 GPa, both high-temperature paramagnetic and low-temperature intermediate valence phases are insensitive to pressure.Our results confirm the first-order nature of the transition between the intermediate valence and magnetic ordered phases with pressure.