Variation of vortex-glass dynamics and critical region with oxygen content in Bi2Sr2CaCu2O8+δ single crystal

A systematic analysis of disorder and anisotropy effects has been performed on the transport data of three oxygen doped Bi2SrCaCu2O8+delta (BSCCO-2212) single crystals obtained in external magnetic field aligned with the crystal c-axis, ranging from 100 Oe to 40 kOe. The result confirms the existence of finite critical region in all cases and ostensible crossover behavior associated with 3-D vortex-glass transition. The maximum widths of the regions ([T* - T-g]/T-g = 0.66, 0.53 and 0.38) as well as the critical exponents (s = 5.3 +/- 1.3, 3.8 +/- 0.7 and 2.8 +/- 0.6) are shown to decrease consistently with lower anisotropy (gamma (2) = 19,500, 8300 and 3000) corresponding to samples with increasing doping. While being responsible for the suppression of first-order melting, the effect of stronger disorder also contributes to larger temperature and field ranges of the critical region. (C) 2001 Elsevier Science B.V. All rights reserved.