Fluctuation induced excess conductivity in the Bi < inf > 1.2 < /inf > Pb < inf > 0.3 < /inf > Sr < inf > 1.5 < /inf > Ca < inf > 2 < /inf > Cu < inf > 3 < /inf > O < inf > y < /inf > compound

Abstract

The temperature variation of resistivity measured for the 110 K phase of the (Bi, Pb)-Sr-Ca-Cu-O system has been analysed to study the excess conductivity due to fluctuations in the mean field region. The resistivity data has been analysed using Aslamazov-Larkin (AL) as well as Lawrence-Doniach (LD) theories for the excess conductivity (Δσ), while the normal conductivity (σn) part was chosen to fit the usual linear equation (a+bT-1 as well as that of Veira and Vidal. We find from our analysis (both from AL and LD fits) that the fluctuations in the order parameter are two-dimensional in nature in the 110 K phase of the Bibased system in contrast to that of YBa2Cu3O7. The estimated value of coherence length ξc (0) is 3.96 Å choosing the interplanar spacing (d) to be the value obtained from the theoretical fit. © 1991.