Superconducting transition temperatures of amorphous bismuth alloy films

Abstract

Measurements have been made of the critical temperatures T of c amorphous bismuth alloy films containing lead, thallium, and antimony in concentrations up to 13 atomic percent. The results indicate that the shift in T is approximately linear in impurity concentration, as c expected. The derivative of T with respect to impurity concentration c is not simply related to the valence or atomic size of the impurity atoms. It is suggested that this may have the same cause as the breakdown of Linde's rule for liquid alloys. The widths of the transitions of the films into the superconducting state were extremely small (- 5 millidegrees). This observation has a direct bearing on our understanding of coherence lengths in superconductors.