Vortex jets generated by edge defects in current-carrying superconductor thin strips

Abstract

At sufficiently large transport currents Itr, a defect at the edge of a superconducting strip acts as a gate for the vortices entering into it. These vortices form a jet, which is narrow near the defect and expands due to the repulsion of vortices as they move to the opposite edge of the strip, giving rise to a transverse voltage V⊥. Here, relying upon the equation of vortex motion under competing vortex-vortex and Itr-vortex interactions, we derive the vortex jet shapes in narrow (ξ≪w≲λeff) and wide (w≫λeff) strips [ξ: coherence length, w: strip width, λeff: effective penetration depth]. We predict a nonmonotonic dependence V⊥(Itr) which can be measured with Hall voltage leads placed on the line V1V2 at a small distance l apart from the edge defect and which changes its sign upon l→−l reversal. For narrow strips, we compare the theoretical predictions with experiment, by fitting the V⊥(Itr,l) data for 1−μm-wide MoSi strips with single edge defects milled by a focused ion beam at distances l=16–80 nm from the line V1V2. For wide strips, the derived magnetic field dependence of the vortex jet shape is in line with the recent experimental observations for vortices moving in Pb bridges with a narrowing. Our findings are augmented with the time-dependent Ginzburg-Landau simulations which reproduce the calculated vortex jet shapes and the V⊥(Itr,l) maxima. Furthermore, with increase of Itr, the numerical modeling unveils the evolution of vortex jets to vortex rivers, complementing the analytical theory in the entire range of Itr.

Source-reported materials — not catalogue approval

Similar papers