Abstract
The anomalous broadening of the -like phonon of R observed in Raman scattering is studied as a function of phonon frequency by substituting various rare earths for R. The onset of broadening starts abruptly at a phonon energy which allows us to unambiguously determine a single, sharp superconducting gap at 2Δ=316 . 2Δ/=4.95±0.10, i.e., R is a strong-coupling superconductor. We find qualitative and quantitative agreement with theory.
- Received 25 May 1990
DOI:https://doi.org/10.1103/PhysRevLett.65.915
©1990 American Physical Society