Effect of thermodynamic fluctuations on the shape and width of the resistive transition in three-dimensional amorphous superconducting alloys

Abstract

Measurements of the fluctuation conductivity above Tc have been made for several bulk amorphous superconducting alloys. The results are compared to existing theories for fluctuation conductivity in three-dimensional superconductors. Agreement with theory is obtained very near Tc, but significant deviations from the predictions of the theory are found for higher temperatures. This is attributed to a breakdown of the Ginzburg-Landau approach. The observed temperature dependence of the fluctuation conductivity was similar in all samples studied and suggests a universal dependence on temperature for bulk amorphous superconductors. The effect of statistical variations in alloy composition (occurring on the scale of the superconducting coherence length ξ on the width of the superconducting transition widths was observed. © 1976 The American Physical Society.