A novel buffered high-Tc superconducting step-edge Josephson junction

A novel high-T-c superconducting (HTS) buffered step-edge Josephson junction is fabricated. A 250 nm PrBa2Cu3O7 (PBCO) layer was epitaxially grown on a (001) MgO substrate by PLD, which acts as a buffered template for a step-edge. Argon-ion milling was used to obtain a step-edge with a step angle of 25 degrees. The step-edge is analysed in terms of an extended Wu and Chen model (Wu and Chen 2006 Rev. Sci. Instrum. 77 1). The model validity is confirmed by the correspondence between the theoretically proposed and experimentally observed step angles. A 150 nm YBa2Cu3O7-delta (YBCO) thin film was accordingly grown over the PBCO step-edge and patterned by standard photolithography. I -V characteristics were obtained by DC and AC excitation of the patterned junctions. The IcRn product values are of the order of 1.6 mV and 0.36 mV at 53 K and 77 K, respectively. These values are higher than typical values found in the literature. The observation of Shapiro steps confirms the presence of the Josephson effect in this novel junction topology.