Abstract
Infrared reflectivity measurements on high-quality single crystals of were performed with polarization perpendicular to the planes (E∥c). The c-axis spectrum shows a dramatic change at , from a featureless spectrum above to the one with a sharp reflectivity edge below . We find that the spectrum below is dominated by the plasma edge arising from the carriers condensed in the superconducting state, not by a superconductong gap excitation, and that the superconducting transition is accompanied by the onset of coherent charge transport along the c axis.
- Received 19 May 1992
DOI:https://doi.org/10.1103/PhysRevLett.69.1455
©1992 American Physical Society