Effect of thermal fluctuations on Josephson vortex dynamics in intrinsic Josephson junctions

We have made a numerical study of the effect of thermal fluctuations on Josephson vortex dynamics in a stack of intrinsic Josephson junctions. Our simulations successfully reproduced the experimental results such as the field dependence of the critical current, the noise- rounded current - voltage characteristics and a periodic oscillation of the Josephson vortex flow resistance. It was confirmed that the oscillation period of the Josephson vortex flow resistance is related to the modulation of the critical current rather than the vortex lattice structure. We found that in the dynamic state the triangular vortex lattice becomes stable independent of the field even at zero temperature. Furthermore, at finite temperature, a thermally activated disordered vortex flow is observed in a low- bias region where the Lorentz force is not large enough to induce the collective flow of vortices.