No abstract

No abstract

No abstract

We present measurements of the specific heat and complete elastic moduli of YbInCu 4 as a function of temperature in order to complement existing thermal expansion data. Together these data allow a complete analysis of the thermodynamics of the first-order isostructural valence transition in YbInCu 4. The Clausius-Clapeyron equation predicts well the measured pressure dependence of the valence transition temperature. Estimates of the Gruneisen parameter from thermodynamic measurements and from pressure-dependent magnetic susceptibility in both the high-temperature and low-temperature phases of YbInCu 4 are in good agreement. On the other hand, a Gruneisen analysis of the change in Kondo temperature at the valence transition fails, emphasizing the importance of carrier-density changes associated with the valence transition, unlike in the case of the ␥-␣ transition in elemental Ce. Finally, we address the issue of precursive rounding in the elastic moduli for temperatures greater than the valence transition temperature and argue that thermodynamically YbInCu 4 's valence transition is indeed first order.

No abstract