Search

Application of Josephson effect in sensors, electronic and metrological devices working at temperature of 77 K requires fabrication of efficient and reproducible high temperature superconducting (HTS) Josephson junctions. In order to enhance the performance of HTS junctions, we introduce multilayered approach to YBCO-based step-edge Josephson junction manufacture. Thin YBCO and multilayered YBCO/NdBCO/YBCO films of a similar thickness (\sim210 nm) were grown by a pulsed-laser deposition technique on MgO (100) substrates with artificially created step edge. Large discrepancies of Ic and Rn values were found between these two types of junction. Results of their structural and electrical properties are reported. [ABSTRACT FROM AUTHOR]

The vortex pinning model based on the presence of the large number of edge dislocations in high quality YBa2Cu3O7 (YBCO) films and multilayers has been refined. By introducing the pinning potential of a chain of individual edge dislocations, we have been able not only to describe the critical current density dependence on the applied magnetic field over its entire range, but also to extract the microstructural parameters in the films, such as interdislocation spacing and average domain size, without employing sophisticated microstructural analysis. The model applicability and its results have been verified with the help of microstructural characterization combined with magneto-optical imaging in YBCO films and multilayers with different properties. [ABSTRACT FROM AUTHOR]

Much smoother surfaces and significantly improved superconducting properties of relatively thick YBa2Cu3O7 (YBCO) films have been achieved by introducing a multilayered structure with alternating main YBCO and additional NdBCO layers. The surface of thick (1 μm) multilayers has almost no holes compared to YBCO films. Critical current density (Jc) has been drastically increased up to a factor >3 in 1 μm multilayered structures compared to YBCO films over entire temperature and applied magnetic field range. Moreover, Jc values measured in thick multilayers are even larger than in much thinner YBCO films. The Jc and surface improvement have been analyzed and attributed to growth conditions and corresponding structural peculiarities. [ABSTRACT FROM AUTHOR]