Fabrication of in-situ superconducting thin films of (Y,Tm)-Ba-Cu-O on SrTiO3, NdAlCaO4 and LaGaO3 substrates

We report in-situ preparation of thin films of the high-Tc-superconductors YBa2Cu3O7−δ and TmBa2Cu3O7−δ by d.c.-magnetron sputtering. The films were deposited on single-crystalline SrTiO3, NdAlCaO4 and LaGaO3 substrates held at temperatures between 720°C and 750°C. The applied method proved to be highly reproducible. X-ray diffraction analysis revealed that the YBa2Cu3O7−δ-films grow highly c-axis oriented or epitaxial, whereas the TmBa2Cu3O7−δ-films tend to grow partially c-axis and a-axis oriented. The transition to the superconducting state (zero resistance) is completed between 84K-86K with onset at about 91K for YBa2Cu3O7−δ. The corresponding data for TmBa2Cu3O7−δ are 79K-81K and 88K