Scaling behavior and 3D-2D dimensional crossover in ceramic Tl2Ba2Ca2Cu3O10-delta high-T-c superconductors

The scaling behavior and dimensional crossover in ceramic Tl2Ba2Ca2Cu3O10-delta high-T-c superconductors in magnetic fields 0 less than or equal to H less than or equal to 2000 Oe, are determined by means of comprehensive studies of I-V curve characteristics. In the low magnetic field region 0 less than or equal to H less than or equal to 2000 Oe, well-defined three-dimensional (3D) vortex-glass phase transition temperatures T-g(H) are found. All of the nonlinear I-V curves above and below T-g(H) can be collapsed into two universal lines with the dynamic and static critical exponents z = 2.4 +/- 0.6, v = 1.0 +/- 0.2, clearly showing that the system is in 3D. When H = 2000 Oe and above, the I-V curves on the log-log scale plot begin to be tortuous and this indicates that the system deviates from the 3D behavior. When H greater than or equal to 6000 Oe, all of the I-V curves can be collapsed into one universal line with critical exponents p = 2.3 +/- 0.2 and v(2d) = 2.0 +/- 0.3, which stands for a two dimensional (2D) vortex-glass scaling phenomenon. Our data show that in the quasi-2D region the characteristic temperature T-0(H) continuously decreases as the magnetic field increases. By extensions of 3D vortex-glass phase transition model and quasi-2D scaling process into the intermediate field region (2000 < H < 6000 Oe), we find a correlation between T-0(H) and T-g(H). Combining results obtained from the three different regions, a complete phase transition line is determined in the whole field region 0 less than or equal to H less than or equal to 12000 Oe.