Scaling behavior of current- voltage characteristics of Y(1-x)CaxBa2Cu3O(7-δ) polycrystalline samples

Abstract

I-V characteristics of polycrystalline Y(1-x)CaxBa2Cu3O(7-δ) samples (x=0.025 and 0.20) have been measured at different temperatures and magnetic fields in the range 0.1 T-6.9 T. The scaling behavior has been established for both samples at all magnetic fields. The dynamic exponent z displays some morphology dependence with higher value for small grain size sample Y0.8Ca0.2Ba2Cu3O(7-δ). The static exponent ν has been determined from ρ vs. T dependence at given magnetic field. The critical exponents are field independent with one only exception (ν - for Y0.975Ca0.025Ba2Cu3O(7-δ) sample). This is connected with the special interrelation between the vortex correlation length, ξ, and intervortex spacing α (ξ \leq α) at all magnetic fields above Tg for this sample and its better pinning.

10 pages, 4 figures, 1 Table