Quadrupolar susceptibility and magnetic phase diagram of PrNi2Cd20 with non-Kramers doublet ground state

In this study, ultrasonic measurements were performed on a single crystal of cubic PrNi2Cd20, down to a temperature of 0.02 K, to investigate the crystalline electric field ground state and search for possible phase transitions at low temperatures. The elastic constant (C-11-C-12)/2, which is related to the Gamma(3)-symmetry quadrupolar response, exhibits the Curie-type softening at temperatures below similar to 30 K, which indicates that the present system has a Gamma(3) non-Kramers doublet ground state. A leveling-off of the elastic response appears below similar to 0.1 K toward the lowest temperatures, which implies the presence of level splitting owing to a long-range order in a finite-volume fraction associated with Gamma(3)-symmetry multipoles. A magnetic field-temperature phase diagram of the present compound is constructed up to 28 T for H || [110]. A clear acoustic de Haas-van Alphen signal and a possible magnetic-field-induced phase transition at H similar to 26 T are also detected by high-magnetic-field measurements.