We report conductivity fluctuation measurements in the La1:82Sr0:18CuO4 high temperature superconducting
material. The conductivity fluctuation analysis was performed by utilizing the concept of the logarithmic derivative
of the conductivity excess. Close and above the critical temperature Tc, we experimentally determine the
occurrence of Gaussian and critical fluctuation regimes. Systematic measurements of conductivity as a function
of temperature were performed for several values of transport current j. Fluctuation analysis close to the zero resistivity
temperature Tc0 was performed and we clearly identified a characteristic exponent, which is analyzed by
the dynamical scaling theory and considering a percolation-like transition in a frustrated and disordered system.
The observation of a glass-like behavior in our experiments permits to interpret our results as corresponding to
a vortex-glass regime. |
