Synthesis and properties of high critical transition temperature superconducting thin films and multilayers grown in situ by 90 degree off-axis sputtering.

摘要

A 90{dollar}spcirc{dollar} off-axis single target magnetron sputtering technique for in situ growth of high T{dollar}sb{lcub}rm c{rcub}{dollar} superconducting thin films has been developed. This technique enables us to grow films with the same composition as the target over a large area, with uniform composition and thickness. Using this deposition process, we have synthesized high quality YBa{dollar}sb2{dollar}Cu{dollar}sb3{dollar}O{dollar}sb7{dollar} thin films with various orientations such as c-axis, a-axis and (103). We have investigated their superconducting DC and RF properties, their normal state properties, and their microstructures. These films are distinctly different from bulk crystals and post-deposition annealed films.; By modifying the sputtering system, various multilayers and superlattices with well-defined modulation wavelengths have been synthesized. First, structurally modulated c-axis YBa{dollar}sb2{dollar}Cu{dollar}sb3{dollar}O{dollar}sb7{dollar}/La{dollar}sb{lcub}rm 2-x{rcub}{dollar}Sr{dollar}sb{lcub}rm x{rcub}{dollar}CuO{dollar}sb4{dollar} superlattices were synthesized with modulation wavelength from 60A to 2000A. Both the critical current density and magnetic field dependence decrease as the modulation wavelength decreases. Second, we have for the first time grown and studied compositionally modulated a-axis YBa{dollar}sb2{dollar}Cu{dollar}sb3{dollar}O{dollar}sb7{dollar}/PrBa{dollar}sb2{dollar}Cu{dollar}sb3{dollar}O{dollar}sb7{dollar} superlattices with modulation wavelengths down to 24A. Transport measurements of these superlattices in magnetic fields perpendicular to the CuO{dollar}sb2{dollar} planes show that each CuO{dollar}sb2{dollar} plane is cut in superconducting or insulating strips depending on whether the rare earth neighbor is Y or Pr.; The development of the in situ deposition process for high T{dollar}sb{lcub}rm c{rcub}{dollar} superconducting thin films and multilayers opens many avenues for superconducting electronic device applications and for model experiments in superconductivity.