Abstract
Dimensional fluctuations of superconducting or- der parameters in YBa2Cu3O7−y + xCr2O3 (x = 0.0, 2.3, 4.4, and 6.1 wt.%) has been analyzed. SEM micrographs re- veal the reduced grain size with the incorporation of mag- netic Cr2O3 particles in the YBCO matrix. XRD graphs show the unchanged orthorhombic structure and improved oxygen ordering in the composite samples. With the increase of Cr2O3 wt.%, it is found that the superconducting tran- sition temperatures determined from standard four-probe method decreases gradually. Excess conductivity fluctuation analysis using Aslamazov-Larkin model fitting reveals tran- sition of two dominant regions (2D and 3D) above Tc .2 D to 3D crossover temperature, i.e., Lawerence-Doniach tem- perature that demarcates dimensional nature of fluctuation inside the grains is influenced by Cr2O3 incorporation in YBCO matrix. The decrease in Lawerence-Doniach tem- perature in the mean field region has been observed as a consequent dominance of the 3D region with an increase in wt.% of Cr2O3 in the composite.
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