Nonlinear Susceptibility Measurement for Quadrupolar Response in a Dilute $\Gamma_{3}$ Non-Kramers Doublet System Pr0.05La0.95Pb3

We measure the temperature dependence of the nonlinear susceptibility $\chi_{3}$, which reflects the fluctuation of quadrupolar moments, in Pr 0.05 La 0.95 Pb 3 with a $\Gamma_{3}$ non-Kramers doublet in the crystal-electric-field ground state to provide evidence of the quadrupolar Kondo effect. Non-Fermi liquid behavior of $\chi_{3}$ with a $-\ln T$ dependence is detected in the [100] and [110] directions below $T\approx 2.5$ K, suggesting the screening of quadrupolar moments. In contrast, $\chi_{3}$ in the [111] direction becomes constant below $T\approx 3$ K. The observed features indicate that a low-lying $\Gamma_{3}$ doublet plays a crucial role in the anomalous properties of Pr x La 1-x Pb 3 .