UNEXPECTED HEAVY-ELECTRON BEHAVIOR AT LOW-TEMPERATURES IN PRINAG2

Specific heat, magnetic susceptibility, and electrical resistivity wer e measured as a function of temperature in polycrystalline PrInAg2. A broad peak, similar to a conventional Kondo anomaly, occurs in the spe cific heat at 400 mK. Below the peak, an enhanced linear contribution is observed with a Sommerfeld coefficient of similar to 6.5 J/mol K-2. This is the first Pr-based compound to display heavy-fermion behavior , and it has a Kondo temperature of similar to 1 K. Inelastic -neutron -scattering experiments by Galera et al. found that the non-Kramers do ublet (Gamma(3)) in PrInAg2 is the ground state with a first excited l evel at 5.9 meV. Since the ground slate does not have a magnetic momen t, our results point to the possibility of a new type of interaction b etween the conduction electrons and the quadrupolar moments of the loc alized 4f electrons. The magnetic susceptibility follows a Curie-Weiss law above similar to 50 K with an effective moment of 3.67 mu(B). At low temperatures, the susceptibility falls below simple Curie-Weiss be havior, and it has a value close to that estimated for a Van Vleck con tribution with the crystal electric field levels observed in neutron s cattering. The electrical resistivity monotonically decreases with tem perature and then saturates below similar to 10 K. A weak decrease is observed in the resistivity around 1 K which is consistent with the sm all Kondo temperature.