Low temperature growth and properties of YBCO single-crystal films

Single-crystal YBa 2 Cu 3 O 7− x thin films with T c =90 K have been prepared on SrTiO 3 (100) at relatively low temperatures by activated reactive evaporation. X-ray examination revealed that the c -axis of the 1000A thick film was perfectly perpendicular to the SrTiO 3 (100) face and the film consisted of microdomains whose structure was orthorhombic. The in-situ reflection high-energy electron diffraction observation during growth of the film on SrTiO 3 (100) and MgO(100) suggests that the initial deposition on both the substrates occurs in the layer-to-layer growth manner. The in-plane lattice spacing of deposit on MgO converted from the bulk value of MgO to that of YBCO while the thickness increased from 12 A to 24 A. Some superconducting and surface-structural properties are also reported.