Magnetic Field Dependence of the Low-Temperature Specific Heat in   PrInAg_2: Support for a Non-Magnetic Heavy-Fermion Ground State
  In order to elucidate the nature of the ground state in the heavy-electron system PrInAg_2, we measured its specific heat for temperatures between 60 mK and 2 K in magnetic fields up to 9 T. The peak maximum of the low temperature anomaly in the specific heat (interpreted as Kondo anomaly) shifts from 0.42 K at zero field to 0.45 K at 6 T, and to 0.5 K at 9 T. The data at 3 T (after subtracting the low temperature tail due to a Schottky anomaly) is practically indistinguishable from the zero field data. A low temperature nuclear Schottky anomaly from a hyperfine enhancement of the Pr nuclei was observed in field. Both enhanced hyperfine interaction and the insensitivity of the specific heat anomaly to fields support the hypothesis that the Kondo effect in this system has a non-magnetic origin. 
R. Movshovich, A. Yatskar, M. F. Hundley, P. C. Canfield, and W. P.   Beyermann