We investigate numerically a long Josephson junction with several phase
pi-discontinuity points. Such junctions are usually fabricated as a ramp
between an anisotropic cuprate superconductor like YBCO and an isotropic metal
superconductor like 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 (SF),
pinned at the corners. We show (a) that the spontaneous formation of SFs
depends on the junction length, (b) that the ground state without SFs can be
converted to a state with SFs by applying a bias current, (c) that the SF
configuration can be rearranged by the bias current. All these effects can be
observed using a SQUID microscope.Comment: ~8 pages, 6 figures, submitted to PR