PENETRATION OF MAGNETIC-FLUX INTO LAYERED SUPERCONDUCTORS WITH TRAPPED CHAINS OF FLUXONS

We consider configurations of the magnetic flux trapped in a layered s uperconductor (superlattice) in the form of oblique strings of Josephs on vortices (one vortex per layer). It is shown that the string consis ting of unipolar Josephson vortices is stable provided the spacing in the string is larger than a certain critical value; otherwise, the str ing consisting of alternating Josephson vortices is stable. Then, a st ring with pinned edges in the presence of a dc bias current is conside red. A critical current density that gives rise to rupture of the stri ng is found. The string plays the role of a specific barrier preventin g penetration of an additional flux quantum into the system. To analyz e this role in detail, we consider collisions of a free vortex with th e string pinned at its edges. The following outcomes of the collision have been found: capture, reflection, destruction of a chain, and elas tic scattering.