Characteristics of Grooved YBCO Josephson Junction Prepared by FIB

We have fabricated a YBa2Cu3O7-x (YBCO) Josephson junction using a focused ion beam (FIB). An MgO substrate was etched by FIB and then a 150-300 nm thick c-axis oriented YBCO film was deposited on the substrate by pulsed laser deposition method. We investigated the relation between the I-V properties of the junctions and the microstructure of the YBCO film surface over the FIB etched groove for different thicknesses of YBCO films. The number of the flux-flow type junctions became large with increasing the film thickness. For the thick film sample which shows flux-flow type behavior, the V-shape of the FIB groove became almost lost at the top surface of the YBCO film and a few grains were observed at the center of the groove.