FABRICATION OF HIGH-TEMPERATURE SUPERCONDUCTING JOSEPHSON-JUNCTIONS ON SUBSTRATES PATTERNED BY FOCUSED ION-BEAM

High aspect ratio trenches were patterned on (100) LaAlO3 substrates b y focused ion-beam milling prior to film deposition. Subsequent YBCO f ilms deposited by pulsed laser deposition were found to break naturall y across these trenches. In situ Au was then deposited to connect the separated YBCO electrodes. Junctions were then patterned across the tr enches to form a superconductor/normal/superconductor configuration. T he resistively shunted junctions exhibited supercurrents up to 86 K. U nder microwave irradiation, the junctions exhibited a number of clear Shapiro steps in the I-V characteristics. The transverse magnetic-fiel d diffraction pattern indicted uniform current distribution across the junction. (C) 1998 American Institute of Physics.