Scaling Behavior of Current- Voltage Characteristics of Y_1-xCa_xBa₂Cu₃O_7-δPolycrystalline Samples

Abstract

I-V characteristics of polycrystalline Y 1-x Ca x Ba 2 Cu 3 O 7-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 Y 0.8 Ca 0.2 Ba 2 Cu 3 O 7-. The static exponent has been determined from vs. T dependence at given magnetic field. The critical exponents are field independent with one only exception (-for Y 0.975 Ca 0.025 Ba 2 Cu 3 O 7sample). This is connected with the special interrelation between the vortex correlation length, , and intervortex spacing () at all magnetic fields above T g for this sample and its better pinning. Keywords: Y 1-x Ca x Ba 2 Cu 3 O 7-polycrystalline samples, I-V characteristics, scaling behavior, critical exponents.