Resistive transition in two-dimensional arrays of superconducting weak links

Abstract

We present results of measurements on large arrays of PbBi/Cu proximity-effect junctions. Extrapolation of the critical current measured at low temperature to the region at and above ${T}_{c}$ allows us to describe the initial drop in resistance by a simple model of the proximity effect, and also to define an appropriate effective temperature $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{T}\ensuremath{\cong}\frac{{E}_{J}({T}_{c})T}{{E}_{J}(T)}$ for describing the vortex-unbinding transition. Nonlinear $I\ensuremath{-}V$ curves above ${T}_{c}$ are described by a crossover function whose form is consistent with the theory of Halperin and Nelson.