Josephson vortex dynamics in Bi2Sr2CaCu2O8+delta intrinsic Josephson junctions under high magnetic field

We have investigated vortex dynamics in Bi2Sr2CaCu2O8 intrinsic Josephson j unctions subjected to magnetic field parallel and perpendicular to the CuO2 planes. We measured mesas with 40 x 40 mum(2) in size containing similar t o 20 intrinsic junctions. The zero field I-V characteristics showed typical hysteretic, multi-branched nature of the intrinsic Josephson effect. In hi gh parallel magnetic field (H > 1.5 T), T-V characteristics showed the flux flow step. The step voltage agreed well with the value estimated from know n junction parameters. The obtained Swihart velocity was about 4.2 x 10(5) m/s, which corresponds to the velocity of the lowest mode electromagnetic w ave of N-coupled stack. The Experimental I-V curves fit well to the model o f Cherenkov radiation including Ohmic and non-linear dissipation terms.