Non-Fermi liquid behavior in dilute quadrupolar system Pr _xLa_1-xPb₃ with x ≤ 0.05

We have studied the low-temperature properties of Pr_xLa _1-x,Pb₃ with non-Kramers Γ₃ quadrupolar moments of the crystal-electric-field ground state, for a wide concentration range of Pr ions. For z ≤ 0.05, the specific heat C/T increases monotonically below T = 1.5 K, which can be scaled with a characteristic temperature T* defined at each concentration x. The electrical resistivity ρ(T) in the corresponding temperature region shows a marked decrease deviating from a Fermi-liquid behavior ρ(T) ∝ T². The Kondo effect arising from the correlation between the dilute Γ₃ moments and the conduction electrons may give rise to such anomalous behavior.