Heat capacity studies in RPd 2Al 3 (R  Ce, Pr, Nd and Sm) systems

Abstract

In this paper we report the results of low-temperature (from 1.7 to 40 K) heat-capacity studies in RPd 2Al 3 (R  Ce, Pr, Nd and Sm). Our heat-capacity data on CePd 2Al 3 and SmPd 2Al 3 agree with those of the previous studies. A λ-type anomaly is observed at 6.0 K for NdPd 2Al 3. A large jump (11 J/mol K) in heat-capacity data near the magnetic transition temperature confirms the bulk magnetic ordering in NdPd 2Al 3. The data for PrPd 2Al 3 do not show any magnetic ordering down to 1.7 K. We have calculated the magnetic contribution of entropy due to 4f electrons of all the samples. The temperature dependence of entropy in PrPd 2Al 3 indicates a nonmagnetic singlet ground state. The magnetic contribution to the entropy for all samples at 40 K is less than the corresponding free ion entropy values (R ln(2 J + 1)). This suggests that there is a large crystal-field contribution to the heat-capacity in this series.