Abstract
We have measured the room-temperature reflectivity of ‘‘90-K’’ single crystals in the frequency range 600–9000 . The reflectivity R in these highly conducting samples (=150 μΩ cm at 290 K) is found to be higher than in previous reports. We fit R to a simple Drude-Lorentz model and compare the fit parameters with the dc transport values. (The effective-mass ratio of the carriers is found to be 2.0, and the scattering rate ħ/τ is 3.1T at room temperature.) Ellipsometry measurements have also been performed using transverse-electric and transverse-magnetic polarizations. The dielectric dispersion derived from ellipsometry shows some important deviations from the Drude-Lorentz model. Reflectivity data from nonsuperconducting crystals of are also reported.
- Received 1 May 1989
DOI:https://doi.org/10.1103/PhysRevB.40.6884
©1989 American Physical Society