Evaluating the critical current magnitude and distribution width of tridimensional Josephson junction arrays

Abstract

In this contribution we present a simple and effective procedure to determine the average critical current of a tridimensional disordered Josephson junction array (3D-DJJA). Using a contactless configuration we evaluate the average critical current and the typical width of the distribution through the analysis of the isothermal susceptibility response to the excitation field amplitude, χ AC (h). A 3D-DJJA fabricated from granular Nb is used to illustrate the method.The low-frequency magnetic response of Nb-AlO x -Nb Josephson junction arrays (JJA) has been investigated by Araujo-Moreira and coworkers 1 ,2 , through the temperature (T ) and excitation field (h) dependence of the AC magnetic susceptibility, χ AC . Based on simulations of a single-plaquette model, they have successfully explained the dynamic reentrance presented by χ AC (T ) for certain values of h, as well as the isothermal susceptibility χ AC (h).Simulated magnetization versus applied field curves for the single-plaquette model, predict that a certain class of arrays would exhibit, upon excitation by a field, a remanent moment in a limited interval of temperatures, depending on the critical current, I c , and other modeling parameters of the junctions. As a matter of fact, the McCumber parameter, β L is the