On the Role of Surface Oxide Impurities in the 'Knee' Effect in Superconducting Tunnel Junctions.
Abstract
The authors present a qualitative model based on the effect of impurity states in the barrier to explain the anomalous 'knee' in the I-V characteristics of superconducting tunnel junctions, they have experimentally confirmed the temperature dependence predicted by the model, and have been able to reproducibly control the appearance, disappearance and the severity of the anomaly by controlled junction fabrication. The junctions were made by evaporating thin films on to the oxidized surfaces of Nb single crystals which had been grown in ultra-high vacua by the floating zone technique. The authors report that control of impurities in the barrier itself (rather than surface effects at the metal-oxide interface) according to the model can completely control the appearance of the anomaly. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 12, 1972
- Accession Number
- AD0745011
Entities
People
- Margaret L. A. Macvicar
- Myron H. Fremmer
- Robert Marc Rose
Organizations
- Massachusetts Institute of Technology