MODIFIED AMBEGAOKAR–HALPERIN MODEL AND DISSIPATION IN THE POLYCRYSTALLINE Ba2YCu3O7-δ SUPERCONDUCTOR

Abstract

The magnetoresistance curves of polycrystalline Ba 2 YCu 3 O 7-δ samples for H=0, 1050 and 4880 G are analyzed using the modified Ambegaokar–Halperin model. The analysis shows the occurrence of a crossover in the R–T curves at a field dependent temperature T BP , revealing that the dissipation in Ba 2 YCu 3 O 7-δ samples is possibly caused by two different mechanisms: vortex-dynamics in the low temperature region (below T BP ) and the order parameter fluctuations in the high temperature region (above T BP ).