YBCO Step-Edge Junctions: Influence of Morphology on Junction Transport

We undertake a detailed investigation of the morphology of YBCO step-edge junctions on MgO substrates using a range of techniques. Differences between the grain boundary structure of step-edge junctions and other more commonly studied [001]-tilt junctions, including good atomic alignment across a ~ 1 nm wide grain boundary and less lattice mismatch and faceting, are highlighted. Transport measurements reveal high IcRn products over a large range of critical current densities, Jc, and a slower reduction in Jc as the step angle increases, compared with [001]-tilt junctions.