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

We have investigated vortex dynamics in Bi2Sr2CaCu2O8 intrinsic Josephson junctions subjected to magnetic field parallel and perpendicular to the CuO2 planes. We measured mesas with 40 x 40 mum(2) in size containing similar to 20 intrinsic junctions. The zero field I-V characteristics showed typical hysteretic, multi-branched nature of the intrinsic Josephson effect. In high 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 known 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 wave of N-coupled stack. The Experimental I-V curves fit well to the model of Cherenkov radiation including Ohmic and non-linear dissipation terms.