Local structure and superconducting properties of YBCO films grown by Co-evaporation

High-rate in-situ YBa ₂Cu ₃O _7-δ (YBCO) film growth was demonstrated by means of electron beam co-evaporation. Even though our oxygen pressure was low, ∼5 × 10 ^-5 Torr, we could synthesize as-grown superconducting YBCO films at a deposition rate of around 10 nm/s, with a critical current density (J _c) of more than 2.0 MA/cm ₂. Relatively high temperatures of around 900 °C have been necessary in this process so far, which suggests that this temperature at a given oxygen activity allows Ba-Cu-O liquid formation along with YBCO epitaxy. We report that the local critical current density shows a clear correlation with the local resistivity. Homogeneous transport properties with a high superconducting transition temperature (89-90 K) are observed in top-faulted region while it is found that the bottom part is found to carry little supercurrent with a large local resistivity. The information derived in this study may be useful in the characterization and optimization of superconducting thin films for electric power and other applications.