Thermodynamic properties of Pb determined from pressure-dependent critical-field measurements

We have carried out extensive low-temperature (1.5-10 K) measurements of the critical field H-c for the element Pb up to a pressure of P=1.2 GPa. From these data, the electronic entropy, specific heat, thermal-expansion coefficient, and compressibility are calculated as a function of temperature, pressure, and magnetic field. The zero-field data are consistent with direct thermodynamic measurements, and the P dependence of T-c and specific-heat coefficient gamma(T,P) allows the determination of the P dependence of the pairing interaction.