Relationship between microstructure and optical properties in high Tc superconductors

Abstract

Spectroscopic ellipsometry investigations on several groups of high Tc superconductors have been performed in the region of 1–5 eV. The optical data have been compared with results of structural studies made by transmission electron microscopy and X-ray diffraction. The dependence of the optical features in the dielectric function on the microstructure of single crystals has been determined. The microstructure in a Cu(1)-O layer has been shown to be closely related to the optical features in the region of 4 eV for (123)-type compounds. The characteristics features in the dielectric function spectra have been determined for single crystals of isostructural (2212)-type phases. In Pb-based (1212)-type single crystals a strong optical anisotropy in the a–b plane has been predicted to be related to an ordering of oxygen vacancies in the Pb-O plane.