The effect of pointlike disorder on current-driven vortex state of Bi2Sr2CaCu2O8+δ

We studied the DC current-driven vortex state of a Bi2Sr2CaCu2O8+delta model in the presence of pointlike disorder via a Monte Carlo simulation. We found that the vortex drift velocity v as a function of temperature T drastically changes twice at a depinning (T-dp) and a melting (T-m) temperature, as is consistent with our two-stage melting scenario. At the low field region, whereas v remains almost zero for T < T-dp, it rapidly grows for T-dp < T < T-m and the Bragg peak intensity survives for T < T-m. We thus give numerical evidence that a moving Bragg glass phase exists for the intermediate temperature regime of T-dp < T < Tm. (C) 2002 Elsevier Science B.V. All rights reserved.