Fluctuation conductivity of Tl-Ba-Ca-Cu-O thin films

Measurements of the in-plane fluctuation-enhanced conductivity of $c$-axis oriented Tl-Ba-Ca-Cu-O thin films have been performed over the temperature range $T_c$ to 240 K. The results were consistent with two-dimensional fluctuation theory and with a linear dependence of the normal resistivity on temperature down to $\frac{(T-T_c)}{T_c}\approx 0.03$. A crossover to three-dimensional fluctuations close to $T_c$ was not found. The width of the superconducting transition appears to be a measure of a distance over which layers fluctuate in a correlated manner.