Abstract
We have measured the heat capacities of and over the temperature range 2–303 K. The availability of data below 10 K plus an estimate of the phonon contribution to the heat capacity based on recent neutron-scattering experiments on the same sample enable us to make a reliable deduction of the electronic contribution to the heat capacity of ; we find as . This is larger than that of any element and large enough for to be classed as a heavy-fermion system. By contrast, in . Two distinct anomalies are seen in the electronic contribution to the heat capacity of , one or both of which may be associated with the formation of the -martensitic phase. We suggest that the large value of may be caused by proximity to a quantum-critical point.
- Received 10 June 2003
DOI:https://doi.org/10.1103/PhysRevLett.91.205901
©2003 American Physical Society