Temperature singularities in reflection spectra of YBaCuO superconducting films in the infrared frequency range

This is the authors' abstract. We don't add key points for this paper.

The reflection spectra of YBaCuO superconducting films with moderate and optimal doping are measured in the IR region (2500–10000 cm−1) by varying temperature in the interval 5–200 K. The experimental results convincingly confirm an optical response to the superconducting transition occurring at the point T=Tc and the sensitivity of optical IR spectra to the phase ordering temperature T=T*>Tc. It is found that samples with optimal doping display reproducible temperature changes at T*>Tc. It is shown that the two-component model of carriers, including light fermions and heavy bosons, is most adequate for a description of the entire body of optical data. Optical data are used for reconstructing the phase diagram for YBa2Cu3O6+x in the T vs. x coordinates.