Possible formation of rectangular Josephson-vortex lattice in narrow Bi-2212 intrinsic Josephson junctions by the enhanced edge effect

Josephson vortex lattice in narrow Bi-2212 intrinsic Josephson junctions have been studied. Formation of rectangular Josephson vortex lattice is expected in narrow width due to the edge effect. Current-voltage (I-V) characteristics were measured as a function of the magnetic field applied parallel to their a-b planes. Maximum zero bias current (I-C.branch) and flux-flow voltage were measured. We observed that the I-C.branch monotonically decreased with magnetic field up to 0.6 T. Above 0.6 T, I-C.branch showed an enhancement, accompanied by an enhancement of flux-flow voltage thus flux-flow speed, up to 1.0 T. This result indicates a change in the configuration of vortex lattices from triangular to other structure (possibly rectangular) by the edge effect in which configuration both the flux-flow voltage and I-C.branch are enhanced due to an increase in the maximum velocity of the vortex lattice. (c) 2005 Elsevier Ltd. All rights reserved.