The Isotope Effect in Superconductivity. I. Mercury

Abstract

The critical magnetic fields of various isotopic mixtures of mercury have been measured as a function of temperature. The critical magnetic field at any temperature is found to decrease with increasing average mass, and the critical temperature also decreases with increasing mass. The relationship ${M}^{\frac{1}{2}}{T}_{c}=\mathrm{const}$, connecting the critical temperature ${T}_{c}$ and the average mass number $M$, is established. Conclusions are drawn concerning the specific heats of the normal and superconducting states of the isotopes.