Single Crystal Growth and Low Temperature Properties of PrNb2Al20

Magnetization, electrical resistivity and specific heat measurements were performed on single crystals of PrNb 2 Al 20 grown by Al self-flux method. No evident anomalies suggesting phase transitions has been found down to 0.6 K. In all measurements, there appear features indicative of crystalline electric field levels with the energy splitting of ∼ 50 K. The monotonically increasing M – H curve at 2 K suggests a nonmagnetic Γ 1 singlet or a non-Kramers Γ 3 doublet ground state. In addition, low-lying excitations in 4 f -electron system remain down to 2 K remain and the associated features (a low temperature upturn in C / T and a non-Fermi liquid behavior in ρ) are observed.