Fabrication of HTS Josephson junctions on substrates prepared by focused ion beam system

YBCO Josephson junctions were fabricated by using a Focused Ion Beam (FIB) of 20-nm diameter gallium ion beam. We first made trenches of 100-nm width and 300-nm depth on LaAlO/sub 3/ (LAO) substrates that were covered by 100-nm chromium (Cr) conducting layer. After removing the conducting layer by chemical etching, YBCO followed by a gold layer was pulsed laser deposited in-situ. The deposited YBCO was disconnected over the trenches and the gold layer filled the trenches and made connections between the separated YBCO so that it formed SNS junctions. We observed proximity coupling up to 86 K.