Abstract
The first polarized infrared-reflectivity measurements of untwinned crystals of as a function of y are reported. We separate the chain and plane contributions to the infrared conductivity, and find that for crystals with ≳50 K the prominent normal state midinfrared feature is associated with the chains. A threshold in the plane conductivity at ∼500 has a strong temperature dependence just below suggesting an association with the superconducting gap. Its temperature dependence above and below is quite similar to that of relevant NMR data, and is suggestive of gap development in the normal state.
- Received 17 July 1991
DOI:https://doi.org/10.1103/PhysRevLett.67.2741
©1991 American Physical Society