Possible Correlated-Electron Behavior from Quadrupolar Fluctuations in PrInAg2

The temperature dependent magnetic susceptibility, specific heat, and electrical resistivity were measured on PrInA${\mathrm{g}}_2$. A broad peak, which is identified as a Kondo anomaly, is observed in the specific heat at $\sim 0.4\mathrm{K}$ with a strongly enhanced linear contribution at lower temperatures. PrInA${\mathrm{g}}_2$ is a Pr-based heavy-fermion compound and has one of the largest known Sommerfeld coefficients of $\sim 6.5\mathrm{J}/\mathrm{mol}{\mathrm{K}}^2$. A new type of nonmagnetic interaction between the conduction electrons and the non-Kramers doublet ground state of the ${\mathrm{Pr}}^{3+}$ ion may be responsible for this behavior. Related features are also observed in the susceptibility and resistivity.