Coherent vortex motion in superconducting nanobridges based on YBaCuO thin films

Submicron bridges in superconducting YBaCuO thin films with typical linear dimensions of about 100 nm have been fabricated. Experimental current-voltage characteristics of these structures are in reasonable agreement with numerical simulations based on true two dimensional viscous vortex motion and indicate the effect of switching from a single path motion at low transport currents to multiple paths at higher currents. The value of the viscous drag coefficient of this vortex motion is found to be about 10/sup -9/ kg/m.sec, which is about two orders of magnitude lower than one estimated from the Bardeen-Stephen model. Critical current densities in the investigated nanobridges are up to 5.10/sup 10/ A/m/sup 2/ at T=4.2 K. The critical current as a function of the width of the bridges indicates the dominating role of edge pinning.<>