Superconducting Thin Films, Composites and Superconducting Junctions
Abstract
The important issue of how the superconducting transition temperature Tc in disordered system changes near the M-I transition where strong localization (k sub F 1 about 1) is expected has been studied in the Mo-Ge system. In the high Mo concentration, which is in the weakly localized regime, Tc decreases linearly with decreasing Mo concentration. In this region the ratio cf electron-phonon coupling constant lambda to the bare density of states N sub b(O) is constant, which is consistent with the Varma-Dynes tight-binding model. An extrapolation of the linear behavior of Tc in this regime yields the disappearance of Tc near 35 at. % Mo. Superconductivity in very thin films of niobium has been investigated. By use of the ion gun which has been installed in the evaporator it has been possible to identify 3 separate mechanisms which contribute to the reduction in Tc as the film thickness is decreased, namely lifetime broadening, proximity effect and localization. A small single grid ion source has been constructed in order to promote the growth of metastable films at low temperatures. Process has been made on a new ultra high vacuum M.B.E. evaporator.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1985
- Accession Number
- ADA223576
Entities
People
- T. H. Gaballe
Organizations
- Stanford University