Response of YBaCuO thin-film microbridges to microwave irradiation

Abstract
Microbridges with widths of about 10 μm were lift-off structured from rf-sputtered YBaCuO thin films and irradiated with microwaves at different temperatures. The bridges contain only a few grains with a typical size of 4 μm and are fully c-axis oriented. The observed current-voltage characteristics exhibit sharp constant voltage steps up to 71 K. An oscillatory dependence of the critical current I0 and the step heights 2In is observed, clearly revealing Josephson-like behavior. From the grain structure, the critical current, and the microwave response, it is very likely that grain boundaries as superconductor-normal conductor-superconductor (SNS) contacts dominate the behavior of the bridges.