Specific heat of PrNi5

Specific-heat measurements have been performed on single-crystalline PrNi5 from 1.3 to 250 K, in order to evaluate the contribution of the Pr subsystem. PrNi5 does not order magnetically down to the lowest temperatures as crystalline-electric-field (CEF) interactions, producing the non-magnetic singlet ground state Γ4, dominate the exchange interactions. Analysis of the specific heat unambiguously establishes the position of the two lowest excited levels at 33.7 K (Γ1) and 45.7 K (Γ6) which levels cannot be observed in inelastic-neutron-scattering experiments. A set of CEF parameters of the Pr3+ ion in the f2 configuration has been evaluated that gives the best account for all known experimental results of this compound. ((orig.))