Experimental Study on Plasticity of Current-driven Vortex Lattices Interacting with Disorder in Bi2Sr2Ca1Cu2O8 Single Crystal

Abstract From the I-V characteristics for as-grown and irradiated Bi2Sr2CaCu2O8+δ single crystals at T=5K (i.e. T → 0) in a magnetic field applied parallel to c axis, we have seen two types of vortex dynamics above the depinning threshold, depending on the vortex-vortex interaction strength (λab/a0). For the as-grown sample, at a low field, the I-V curves show steps that clearly indicate a “fingerprint phenomenon” since they reflex the current dependence of the differential resistance rd(I). This can be ascribed to vortices flowing through uncorrelated channels for the highly defective lattice. As field sufficiently increase, these peaks merge to become broader ones indicating a crossover from filament type to braid river type. In contrast, in the irradiated sample, the pinning is found to be individual at low fields and collective when the vortex-vortex interactions are involved.