On the origin of reentrance in 2D Josephson Junction Arrays

TL;DR

This study investigates the magnetic properties of 2D Josephson junction arrays, revealing that reentrant susceptibility behavior is linked to the Stewart-McCumber parameter and providing a phase diagram to distinguish reentrant from non-reentrant states.

Contribution

It introduces a single-plaquette approximation to fit experimental data and maps the phase boundary between reentrant and non-reentrant behaviors in 2D-JJAs.

Findings

Reentrant AC susceptibility is linked to the Stewart-McCumber parameter.

A phase diagram delineates reentrant and non-reentrant regimes.

Experimental data are successfully modeled using the approximation.

Abstract

A comparative study of the magnetic properties of shunted and unshunted two-dimensional Josephson junction arrays (2D-JJA) is presented. Using a single-plaquette approximation of the 2D-JJA model, we were able to successfully fit all our experimental data (for the temperature, AC and DC field dependencies of susceptibility) and demonstrate that the dynamic reentrance of AC susceptibility is directly linked to the value of the Stewart-McCumber parameter \beta_C. Based on extensive numerical simulations, a phase diagram \beta_C vs \beta_L is plotted which demarcates the border between the reentrant and non-reentrant behavior in the arrays.