FABRICATION AND STRUCTURAL-ANALYSIS OF YBCO/PBCO SUPERLATTICES

Abstract

We have fabricated various YBCO/PBCO superlattices and investigated the microstructure by X-ray diffraction and transmission electron micrography. The superlattices were grown in situ on SrTiO3 substrates by pulsed-laser deposition. The X-ray diffraction spectra showed the formation of a high-quality superlattice structure with the c-axis normal to the substrates. In the spectra, the satellite peaks between the main peaks indicated the growth of well-defined interfaces between the YBCO and PBCO layers, which was also supported by cross-sectional transmission electron micrography. The Laue oscillations observed in the X-ray spectra confirmed that the surfaces of the superlattice films were highly uniform. The superlattice composed of two-unit-cell-thick YBCO layers showed superconductivity with a relatively broad transition width, although the normal state revealed semiconducting characteristics.