SPECIFIC-HEAT OF CENIXPT1-X PSEUDOBINARY COMPOUNDS AND RELATED DILUTE ALLOYS

The low-temperature specific heat of CeNixPt1-x compounds has been investigated from x=0 to X=1. These compounds evolve from a Pauli paramagnet (CeNi) to a Kondo ferromagnet (CePt), with a crossover around x=0.90. The reduction of the magnetic entropy at T(C) has been used to illustrate the increasing 4f-sd hybridization with increasing Ni content, related to a decrease of the cell volume. This effect has been confirmed by the results obtained on Y and La diluted compounds which have opposite volume effects. The relations between the jump in the specific heat at T(C), the magnetic moment, and the ratio T(K)/T(C) have been analyzed. The values of the electronic heat capacity gamma vary as almost-equal-to 1/T(K) in the nonmagnetically ordered compounds in accord with the standard theory. However in the magnetically ordered compounds gamma increases with T(K) in accord with the resonance-level model developed by Bredl et al. [Z. Phys. B 29, 327 (1978)].