High-T_c Superconducting YBa₂Cu₃O_7-δ Films and YBa₂Cu₃O_7-δ/PrBa₂Cu₃O_7-δ Superlattices Deposited by Laser Ablation

Abstract

High T_c superconducting YBa₂Cu₃O_7-d thin films and YBa₂Cu_37-δ/PrBa₂Cu₃O_7-δ superlattices with various periods and layer thicknesses were deposited by laser ablation on SrTiO₃ (100) single crystal substrates using an XeCl excimer laser (λ = 308 nm). The structure of the films was studied by SEM/EDS and X-ray diffraction. The films and superlattices deposited in an in situ process were epitaxial with the c-axis perpendicular to the substrate surface and the a- and b-axes parallel with the SrTiO₃ [100] or [010] directions. The electrical properties were studied by measuring the current-voltage characteristics, resistivity and critical current. For the in situ deposited YBa₂Cu₃O_7-d films the zero resistivity temperature was 87 to 90 K and the critical current at 77 K was above 2 × 10⁶ A/cm². For the films deposited at room temperature and post annealed under in situ deposition conditions, the critical temperature was the same, but the critical current was 0.5 × 10⁶ A/cm².