Thermodynamic Behavior of Ce Compounds Close to a T ->0 Critical Point

Abstract

There is a reduced group of Ce very heavy Fermions (VHF) which do not order magnetically down to at least T ≈ 500 mK because they are very close to a T ord = 0 critical point. These compounds are at the top of the lim T→ 0 C m /T specific heat values because they collect very high density of low energy excitations. From the analysis of C m (T)/T and entropy S m (T) dependencies performed on selected CePd 3 M x ternaries (where M = B and Be) a quantitative evaluation of an upper limit for the density of excitations can be proposed. These observations exclude any evidence of C m (T)/T divergency as T→ 0 in agreement with thermodynamic laws. A comparison with selected Yb-base VHF supports these features.