Abstract
We present optical conductivity data for over a wide range of frequencies and temperatures for and 0.09. Both materials show evidence of being good Drude metals with the infrared data in reasonable agreement with dc resistivity measurements at low frequencies. An absorption threshold is seen at approximately 700 . In the cobalt-doped material, we see a superconducting gap in the conductivity spectrum with an absorption onset at suggestive of weak to moderately strong coupling. The pure material is in the clean limit and no gap can be seen. We discuss the data in terms of the electron-phonon interaction and find that it can be fit below 600 with a plasma frequency of 3.3 eV and an electron-phonon coupling constant using an spectrum fit to the resistivity.
- Received 20 August 2001
DOI:https://doi.org/10.1103/PhysRevB.65.064506
©2002 American Physical Society