Fluctuation-induced conductivity and dimensionality in the new Y-based Y_3Ba_5Cu_8O_(18)-x superconductor

摘要

The fluctuation conductivity measurement on the new Y-based Y _3Ba_5Cu_8O_(18)-x superconductor is presented. The dimensional crossovers between different temperature regimes were analyzed with Aslamazov-Larkin (AL) theory and a good quantitative agreement was achieved for the experimental data. For our data, the mean field regime is dominated by 2D AL fluctuations. Our results reveal the occurrence of critical fluctuation regime in consistent with the prediction of the full dynamic 3D XY model. We found the dynamical critical exponent to be z = 3.4 for our data. We analyzed also the excess conductivity data by Hikami-Larkin theory and estimated the phase relaxation time.