Proportionality between gamma and T-K near the heavy fermion to intermediate valent transformation

In a systematic analysis performed on binary and ternary Ce compounds, whose magnetic properties change by alloying the Ce ligand, a critical concentration (X-cr) was observed as a change in the concentration dependence of the volume, paramagnetic temperature, electrical resistivity, linear specific heat coefficient (gamma) and X-ray absorption edges. Such a change of regime is independent of the magnetic phase boundary (at x = x(0)) and observed in magnetic (M) or heavy fermion (HF) to intermediate valent transformations, but not in a M to HF one. In both cases gamma(x) increases between x(0) and x(cr), despite the increase of the Kondo temperature (T-K), in an apparent violation of the gamma similar to T-K (1) relationship. This unexpected behaviour is discussed in terms of the transference of degrees of freedom and the change of the ground state degeneracy respectively.