Fluctuation effects of the superconducting order parameter in high-${\mathit{T}}_{\mathit{c}}$ cuprate superconductors are investigated in connection with the mass-enhancement effect on the phenomenological Ginzburg-Landau theory and the Gaussian fluctuation theory. Large fluctuations of the order parameter, originating in a large mass enhancement caused by strong electron correlation, play an essential role in the determination of ${\mathit{T}}_{\mathit{c}}$ in high-${\mathit{T}}_{\mathit{c}}$ superconductors. It is shown that a simple linear relation between ${\mathit{T}}_{\mathit{c}}$ and ${\lambda }_0^{\mathrm{-}2}$ holds in the system with low doping, where ${\lambda }_0$ is a magnetic penetration depth at T=0 K.

• Received 8 December 1989

DOI:https://doi.org/10.1103/PhysRevB.41.11588