ab-oriented YBa₂Cu₃O₇ thin film grown on c-axis layer by radio frequency sputtering

YBa₂Cu₃O₇ films can be grown on different substrates by the off-axis ac magnetron sputtering method. Films in the ab orientation tend to grow at a lower substrate temperature than c-axis films. However, as the temperature is lowered, all the substrates we have tested, except for SrTiO₃, form amorphous phases that degrade the quality of the films being made. In this manuscript it is shown that if a thin layer of c-axis film is deposited on the substrate first, then it effectively reduces the formation of the amorphous phases and improves the film quality significantly.