Abstract
Superconducting () single crystals are investigated by broad-band infrared spectroscopy. Below K, a superconducting gap forms at , causing the reflectivity to sharply rise to unity at low frequency. In the range of the gap, the optical conductivity can be perfectly described by BCS theory with an -wave gap and no nodes. From our analysis of the temperature-dependent conductivity and spectral weight at , we deduce an increased interband coupling between hole and electron sheets on the Fermi surface when approaches .
- Received 4 November 2010
DOI:https://doi.org/10.1103/PhysRevB.83.100503
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