Infrared Reflectivity and Conductivity of Tl2Ba2CaCu2O8 Crystals: Evidence for Nonconducting Behaviour of the TlO Layers

Results of infrared reflectivity measurements of Tl2Ba2CaCu2O8 crystals for the electric-field vector parallel to the (a, b)-plane suggest that the TlO layers are almost nonconducting. This follows from the similarity of the observed reflectivity with that of YBa2Cu3O7-δ for the electric-field vector perpendicular to the chain direction. The conductivity in the CuO2 layers is analysed using Eliashberg's strong electron-phonon coupling theory.