Superconductive Tunnelling Measurements on Thin Films

Abstract

The properties of superconducting lead have been studied using the technique of electron tunnelling through a thin insulating barrier. Certain features in the second derivative of the current voltage characteristic of this tunnelling mechanism have been related to the phonon spectrum of lead. In addition, a small amount of bismuth impurities have been added and the effect of these impurities on the superconducting density of states reported. In particular, both the superconducting energy gap has widened and the phonon spectrum of lead altered with the addition of these impurities.