  Based on specific heat (C_m) and entropy evaluation, different magnetic phase
diagrams of Ce compounds can be recognized: I) with the entropy of the ordered
phase (S_MO) decreasing with their order temperature (T_ord): S_MO => 0 as
T_ord => 0, being these systems the only candidates for Quantum Critical
behavior. II) with phase boundaries ending at a finite temperature Critical
Point because their Cm(T_ord) jumps (\Delta C_m) do not decrease sufficiently
with T_ord producing a S_MO bottleneck, and III) those showing a transference
of degrees of freedom to a non-magnetic heavy fermion (HF) component, with
their \Delta C_m vanishing at T >> 0. There is also a IV) group of Ce HF
fermions which do not order magnetically because they are tuned at T_ord = 0.
These compounds are at the top of the lim(T=>0) of \delta S_m/\delta T = \gamma
. values because they collect the highest density of low energy excitations.
From the analysis of Cm(T)=T and S_m(T) results performed on these selected Ce
ternaries, a quantitative determination of an upper limit for the density of
excitations is obtained, excluding any evidence of C_m(T)/T divergency at T =>
0 in agreement with thermodynamic laws.
