Fluctuation effects and mass enhancement in high-Tc cuprate superconductors.

Abstract

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 ${\ensuremath{\lambda}}_{0}^{\mathrm{\ensuremath{-}}2}$ holds in the system with low doping, where ${\ensuremath{\lambda}}_{0}$ is a magnetic penetration depth at T=0 K.