Collective dynamics of Josephson fluxons in Bi2Sr2CaCu2O8+delta intrinsic junctions

Abstract

The dynamic characteristics of Josephson fluxons in naturally stacked intrinsic Josephson junctions in Bi2Sr2CaCu2O8+delta single crystals were studied experimentally. The Josephson fluxons were generated either by irradiating microwaves or by applying dc magnetic fields in parallel with the junction planes. In the presence of a finite tunneling bias current the fluxons are driven along the junctions in resonance with the excitation modes of Josephson plasma and thus exhibit a variety of dynamic characteristics. Thus in the flux-flow state of fluxons in both cases above, for a relatively low vortex density, sub-branch splitting of the 'supercurrent' branch in the current-voltage (I-V) characteristics was observed, which corresponded to different plasma excitation modes. For a higher vortex density, on the other hand, all the quasiparticle branches merged into a single non-hysteretic I-V curve which exhibited step-like kink features, very similar to the recently predicted ones corresponding to different moving fluxon patterns. The detailed agreement with the theoretical prediction, however, is yet to be confirmed. (C) 2002 Elsevier Science B.V. All rights reserved.