As-grown preparation of high-critical-temperature superconducting Y1Ba2Cu3O7−x films by radio-frequency plasma flash evaporation

As-grown superconducting Y1Ba2Cu3O7−x films were successfully synthesized on (100) MgO and (100) SrTiO3 substrates by radio-frequency (rf) plasma flash evaporation, in which fine powder mixtures of constituents are continuously injected into an rf plasma, co-evaporated, and co-deposited onto a substrate. In particular, films deposited on a (100) SrTiO3 substrate at 670 °C exhibited a superconducting transition temperature Tc of 92 K and critical current density Jc of 3×105 A/cm2 under zero magnetic field at 77 K. The excitation temperatures of several species during the depositions were estimated from optical emission spectroscopy. The temperature of Y+ was a few thousand degrees lower than that of Ba+ and Cu. The difference in these excitation temperatures revealed that this plasma process was a nonequilibrium deposition.