Abstract
Current-imaging tunneling spectroscopy (CITS) was performed on cold-cleaved single crystals of at 20 K. CITS data include curves taken simultaneously with a topographic scanning tunneling microscopic image. curves taken on CuO chains show an energy gap of about 20 meV which disappears near oxygen vacancies. We explain several features of large-junction measurements, photoemission spectroscopy, and single-point spectroscopy in terms of local effects detected by our CITS measurements. Finally, we consider the possibilities that this energy gap is due to either a charge-density wave or proximity-coupled superconductivity from the planes.
- Received 26 April 1995
DOI:https://doi.org/10.1103/PhysRevLett.75.1387
©1995 American Physical Society