Observation of Josephson-vortex-flow submodes in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions

Stacked intrinsic Josephson junctions form in highly anisotropic high-Tc superconductors such as Bi2Sr2CaCu2O8+x. Josephson-vortex dynamics in such systems attracts much research interests, both academic and application points of view. In a dense Josephson-vortex state (in the range of 4-5 T external magnetic field applied in parallel with the junction planes) of Bi2Sr2CaCu2O8+x stacked intrinsic Josephson junctions vortex-flow motion is in resonance with the collective plasma oscillation modes. With increasing magnetic fields beyond ∼2 T hysteretic quasiparticle branches keep shrinking, while the collective Josephson-vortex-flow branches start appearing and become clearer. The Josephson-vortex-flow branches split into multiple sub-branches corresponding to the number of coupled junctions in the stack. The low-bias characteristics of the Josephson-vortex-flow sub-branches fit well to the inductive-capacitive hybrid coupling model.