Abstract
We studied the electronic -axis conductivity of by far-infrared ellipsometry. The substitution of by makes the overdoped regime accessible and decouples the electronic properties of planes and CuO chains. We find evidence that the unusual and dependence of in the normal state, in particular, the “pseudogap,” is determined by the planes which confine the charge carriers. In the overdoped regime this confinement is relaxed. Simultaneously, the superconducting energy gap is reduced and a large fraction of the quasiparticles remains unpaired below .
- Received 9 October 1997
DOI:https://doi.org/10.1103/PhysRevLett.80.1762
©1998 American Physical Society