Augmentation systems

Abstract

We investigate numerically a long Josephson junction with several phase pi-discontinuity points. Such junctions were recently fabricated as a ramp between an anisotropic cuprate superconductor such as YBa2Cu3O7 and an isotropic metal superconductor such as Nb. From the top, they look like zigzags with pi jumps of the Josephson phase at the corners. These pi jumps, at certain conditions, lead to the formation of half-integer flux quanta, which we call semifluxons (SFs), pinned at the corners. We show that (i) the spontaneous formation of SFs depends on the junction length, (ii) the ground state without SFs can be converted to a state with SFs by applying a bias current, (iii) the SF configuration can be rearranged by the bias current. All these effects can be observed using a superconducting quantum interference device microscope.