Scaling behavior of current- voltage characteristics of Y(1-x)CaxBa2Cu3O(7-{\delta}) polycrystalline samples

I-V characteristics of polycrystalline Y(1-x)CaxBa2Cu3O(7-{\delta}) 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-{\delta}). The static exponent {\nu} has been determined from {\rho} vs. T dependence at given magnetic field. The critical exponents are field independent with one only exception ({\nu} - for Y0.975Ca0.025Ba2Cu3O(7-{\delta}) sample). This is connected with the special interrelation between the vortex correlation length, {\xi}, and intervortex spacing {\alpha} ({\xi} \leq {\alpha}) at all magnetic fields above Tg for this sample and its better pinning.

E. Nazarova, K. Nenkov, K. Buchkov, A. Zahariev · 2010