Ratio between the sub-THz reflectivity of the ab planes below Tc and in the normal phase at 10 K. The lines are fits based on a Mattis-Bardeen reflectivity below Tc and on a Drude model at 10 K (see text). The upper inset shows the magnetic moment measured by cooling the sample in a field of 10 Oe, showing the superconducting transition at K. The lower inset shows a check on data reproducibility, performed by dividing two subsequent spectra of 256 scans.
