A STUDY OF SUPERCONDUCTIVITY IN LEAD–BISMUTH ALLOYS USING ELECTRON TUNNELING TECHNIQUES

Abstract

Some of the properties of superconducting lead–bismuth alloy films have been investigated using electron tunneling techniques. The superconducting energy gaps and transition temperatures as well as the effective tunneling density of electron states near the end point of the phonon spectrum have been measured for various compositions of this alloy system. It was found that pure bismuth films as well as bismuth films containing small amounts of lead are not superconducting above 1 °K. The results also indicate that for alloys with bismuth concentrations between about 35% and 75%, superconductivity is due partially to a proximity effect.