Thermodynamic Properties of Molybdenum in Its Superconducting and Normal State

We have carried out specific-heat measurements on four samples of molybdenum in the normal and superconducting states between 0.4 and 4°K. For one sample, a detailed investigation was also made of the specific heat, the latent heat, and the critical-field curve in the region of the normal transition point $T_c$ and in fields up to 5 G. For a reversible transition, these quantities are related by thermodynamic equations and they were found to be consistent within experimental error. The transition temperatures in zero field were found to be 0.915, 0.917, 0.918, and 0.83°K, respectively. No lambda anomaly in the specific heat could be detected there. From the measurements between 0.4 and 0.9°K, the electronic specific heat in the superconducting state was derived and compared to that expected from the BCS theory. The deviations from the theory at the low-temperature end are thought to be due to anisotropy in the energy gap. The energy-gap parameter and the critical-field curve were also deduced and compared with results from acoustic measurements.