Excess conductivity studies in pure and Ag doped 85 K phase in BiSrCaCuO system

Abstract

The temperature variation of resistivity measured for the pure and Ag doped compounds in BiSrCaCuO system with Tc (zero) ranging from 78.9 K to 86.5 K, have been analysed to study the excess conductivity due to fluctuations in the mean field region. The excess conductivity data have been analysed using Aslamazov - Larkin (AL) as well as Lawrence - Doniach (LD) expressions. We find from our analysis that all the samples studied show two-dimensional fluctuations of the order parameter in the mean field region with a cross-over to the three dimensional fluctuations very close to the transition temperature (Tc < T ≤ Tc + 1.1K). The average value of estimated coherence length along c-direction for teh compounds studied is 1.57A, using the unit cell c-parameter to be the inter-layer spacing (d) for the LD fit. © 1992.