Effects of Pressure on Cage-Structural Compound Ce3Pd20Ge6

We have measured the electrical resistivity of clathrate Ce3Pd20Ge6 under high pressure up to 3.86 GPa in order to investigate pressure effects on two successive phase transitions: O02-type ferroquadrupole order on Ce-8c site at TQ = 1.2 K and antiferromagnetic order on Ce-4a site at TN = 0.75 K. With applying pressure, TQ stays nearly constant at low pressures and gradually decreases above 2 GPa, while TN first increases and then decreases above 2.5 GPa. From these results, critical pressures, where TN and TQ become 0, are roughly estimated to be around 5−6 GPa. In addition, we found that the magnetic resistivity, which is obtained by subtracting the resistivity of La3Pd20Ge6 from that of Ce3Pd20Ge6, exhibits –InT dependence in two different temperature ranges, suggesting presence of two different Kondo temperatures originated in the two crystallographic Ce-sites.