YBACUO JUNCTIONS APPLIED TO MICROWAVE PHASE SHIFTERS

YBaCuO Josephson junctions in series were fabricated by focused Ga ion beams (FIB) to form them in a flat and lateral configuration on MgO s ubstrates. The origin of the junction was investigated and we had foun d that the YBaCuO grain boundary and the defused Ga into the YBaCuO pl ay important roles to form a Josephson Junction. A mechanism of the ju nction was proposed by measuring cross-sectional transmission electron microscopy (TEM) images and their X-ray spectra of Ga, Y, Ba, Cu, Mg and O. We applied them to microwave devices with functions of phase sh ift and frequency down conversion at 60 GHz.