Single-Site Non-Fermi Liquid Behaviors in a Diluted 4$f^2$ System Y$_{1-x}$Pr$_x$Ir$_2$Zn$_{20}$

Electrical resistivity $\rho(T)$ and specific heat $C(T)$ measurements have been made on the diluted 4$f^2$ system Y(Pr)Ir$_2$Zn$_{20}$. Both data of $\rho$ and magnetic specific heat $C_{\rm m}$ per Pr ion are well scaled as a function of $T/T_{\rm 0}$, where $T_{\rm 0}$ is a characteristic temperature of non-Fermi liquid (NFL) behaviors. Furthermore, the temperature dependences of $\rho$ and $C_{\mathrm{m}}/T$ agree with the NFL behaviors predicted by the two-channel Kondo model for the strong coupling limit. Therefore, we infer that the observed NFL behaviors result from the single-site quadrupole Kondo effect due to the hybridization of the 4$f^2$ states with multi-channel conduction electrons.