Abstract
New tunneling data are reported in which show quasiparticle excitation gaps, Δ, reaching values as high as 60 meV for underdoped crystals with . These energy gaps are nearly 3 times larger than those of overdoped crystals with similar . Despite the large differences in gap magnitude, the tunneling spectra display qualitatively similar characteristics over the entire doping range. Detailed examination of the spectra, including the Josephson product measured in break junctions, indicates that these energy gaps are predominantly of superconducting origin.
- Received 23 September 1998
DOI:https://doi.org/10.1103/PhysRevLett.83.1018
©1999 American Physical Society