Reduction of strain in high temperature superconductor thin film devices

Multilayer buffer layers containing BaZrO3 thin films on the bottom and SrTiO3 thin films on the top were successfully applied to improve the epitaxial growth of the YBa2Cu3O7-x (YBCO) films on the MgO substrates, which have the best correspondence of the thermal expansion coefficient with one of YBCO. The HRTEM and X-ray diffraction studies demonstrated pure c-axis orientation and absence of the in-plane misoriented grains in the YBCO films grown on the buffered MgO substrates. High superconducting parameters and no cracks were observed in such YBCO films even at their thicknesses >>1 μm. The multilayer flux transformers having total thickness ∼2-μm were prepared on the buffered MgO substrates and demonstrated an improved insulation between the superconducting layers and an increased dynamic range compared to flux transformers on SrTiO3 substrates