Josephson junctions based on c-axis oriented YBaCuO/PrBaCuO/YBaCuO trilayers

We have fabricated sandwich SNS (superconductor/normal metal/superconductor) junctions using in-situ grown c-axis oriented YBaCuO/PrBaCuO/YBaCuO trilayers. We observe supercurrents for PrBaCuO thicknesses up to 130 nm at 4.2 K. To confirm or rule out the presence of shorts through the barrier, the junction behaviour has been further characterised. Magnetic-field and PrBaCuO thickness dependences of the critical current, as well as a correct scaling with the junction area of both the critical current and the normal resistance, appear to indicate a reasonable uniformity for the barriers on the scale of the size of the junctions, typically 10 μm. These results suggest that either we are observing real c-axis transport in PrBaCuO or, if the behaviour is defect dominated, that the criteria commonly used to demonstrate good device behaviour should be applied carefully. The temperature dependence of the junction critical current and normal resistance are also reported and compared.