Superconducting Tunneling on Bulk Niobium

Abstract

Tunneling effects are observed in superconducting Nb-Nb oxide-Pb sandwiches. The current (I) and DELTA I/ DELTA V across the dielectric Nb oxide films ( approximately 5OA) are found as functions of voltuge (V). A maximum in DELTA I/ DELTA V is found around V = 2.75 to 2.85 mv, at temperatures from 4.2 to 1.9 deg K respectively. This maximum is correlated with the superconducting energy gap in Nb. (T.F.H.)