Isotope Effects in Low Temperature Superconductors

The critical temperatures of different isotopes of osmium and of zinc have been measured. The results are that Os has no isotope effect, while with Zn the critical temperature is proportional to M
^−½.
These findings, together with our previous work on ruthenium, are consistent with the statement that there is no isotope effect for the transition elements, whereas the full M
^−½
effect exists for nontransition elements.