Enhanced surface superconductivity in Ba(Fe0.95Co0.05)2As2
Abstract
We present direct evidence for an enhanced superconducting Tc on the surface of cleaved single crystals of Ba(Fe0.95Co0.05)2As2. Transport measurements performed on samples cleaved in ultra-high vacuum show a significantly enhanced superconducting transition when compared to equivalent measurements performed in air. Deviations from the bulk resistivity appear at 21 K, well above the 10 K bulk Tc of the underdoped compound. We demonstrate that the excess conductivity above the bulk Tc can be controllably suppressed by application of potassium ions on the cleaved surface, indicating that the enhanced superconductivity is strongly localized to the sample surface. Additionally, we find that the effects of the potassium surface dosing are strongly influenced by the presence of residual gas absorbates on the sample surface, which may prevent effective charge transfer from the potassium atoms to the FeAs plane. This further supports the conclusion that the effects of the dosing (and enhanced superconductivity) are localized within a few layers of the surface.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 10, 2020
- Source ID
- 10.1063/1.5133647
Entities
People
- Brendan D. Faeth
- Christopher Parzyck
- Gordon N. Tam
- Greg R. Stewart
- Kyle Shen
Organizations
- Air Force Office of Scientific Research
- Cornell University
- Division of Graduate Education
- Gordon and Betty Moore Foundation
- National Science Foundation Directorate for Mathematical & Physical Sciences
- United States Department of Energy
- University of Florida