Superconductivity in a new Pb1-xZnxSr2LaCu2Oy (x=0.1, 0.3 and 0.5) system: an optical reflectivity study on Pb0.9Zn0.1Sr2LaCu2Oy superconducting oxide

A new superconducting series, viz., Pb1-xZnxSr2LaCu2Oy for x = 0.1, 0.3 and 0.5, has been synthesized by a solid state reaction method. The highest superconducting transition temperature (Tc ∼ 23 K) is observed for x 0.1. Tc is found to decrease with higher Zn concentration, and metal-like normal state behaviour is exhibited for all concentrations of Zn. The X-ray diffraction lines could be fitted to a tetragonal structure, yielding the lattice parameters a and c. Room temperature optical reflectivity spectra in the UV-Vis-NIR range (0.6 to 6.2 eV) for the superconducting sample Pb0.9Zn0.1Sr2LaCu2Oy have been analyzed by the Kramers-Kronig method. This analysis revealed a few interesting features like the absence of an absorption peak around 1.7 eV and the appearance of a hump-like feature around 4.1 eV, distinguishing this superconducting cuprate from other high-Tc cuprates. (orig.)