Abstract
We have performed both Josephson and quasiparticle tunneling in vacuum tunnel junctions formed between a conventional superconducting scanning tunneling microscope tip and overdoped single crystals. A Josephson current is observed with a peak centered at a small finite voltage due to the thermal-fluctuation-dominated superconducting phase dynamics. Josephson measurements at different surface locations yield local values for the Josephson product. Corresponding energy gap measurements were also performed and a surprising inverse correlation was observed between the local product and the local energy gap.
- Received 15 April 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.037002
©2008 American Physical Society