Properties of Superconductor-Normal Metal-Superconductor Microbridges.
Abstract
This theses describes the fabrication and electrical measurement of short, high resistance (R approx. 1 ohm) superconductor-normal metal-superconductor microbridges. These small (length and width as small as 200 nm), planar structures were produced using electron-beam lithography and ion-beam etching. Lead-copper-lead structures were primarily studied; other materials were also briefly investigated. The small cross section of the bridges resulted in a uniform current distribution in the bridges at all temperatures, thus enabling the experimental determination of the critical current versus temperature relation for all temperatures between T sub c and 0.05 T sub c, where T sub C is the transition temperature of the electrodes. The low-voltage current-voltage (I-V) characteristics were studied in detail. Constant-voltage steps were observed in the I-V curves for all frequencies of microwave radiation used. The high resistance of these samples permitted measurement of the I-V curves for voltages much greater than the energy gap of the electrodes. A high-voltage peak in the dV/dI curves was observed, and it was speculated that this peak was due to an extra dissipation in the electrodes. In addition, the low-voltage resistance was found to have a temperature dependence which agreed with the phenomenological theory of Pippard et al., a theory which attributes the extra resistance to energy dissipation in the electrodes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 21, 1980
- Accession Number
- ADA087512
Entities
People
- John Michael Warlaumont
Organizations
- Cornell University School of Applied and Engineering Physics