COHERENT VORTEX MOTION IN SUPERCONDUCTING NANOBRIDGES BASED ON YBACUOTHIN-FILMS

Submicron bridges in superconducting YBaCuO thin films with typical li near dimensions of about 100nm have been fabricated. Experimental curr ent-voltage characteristics of these structures are in reasonable agre ement 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 f ound to be about 10(-9) kg/m . sec, which is about two orders of magni tude lower than one estimated from the Bardeen-Stephen model. Critical current densities in the investigated nanobridges are up to 5.10(10)A /m(2) at T=4.2K. The critical current as a function of the width of th e bridges indicates the dominating role of edge pinning.