Diluted Josephson-junction arrays in a magnetic field: phase coherence and vortex glass thresholds

TL;DR

This paper investigates how random dilution affects phase coherence and vortex glass formation in 2D Josephson-junction arrays under magnetic fields, revealing critical thresholds for superconductivity and vortex ordering.

Contribution

It introduces a detailed analysis of dilution effects on phase coherence and vortex glass thresholds, supported by numerical defect energy calculations for specific flux values.

Findings

Superconducting transition temperature vanishes at a critical dilution level.

Vortex ordering remains stable up to a higher dilution threshold.

Array behaves as a zero-temperature vortex-glass between two critical dilution points.

Abstract

The effects of random dilution of junctions on a two-dimensional Josephson-junction array in a magnetic field are considered. For rational values of the average flux quantum per plaquette $f$, the superconducting transition temperature vanishes, for increasing dilution, at a critical value $x_S(f)$, while the vortex ordering remains stable up to $x_{VL}>x_S$, much below the value $x_p$ corresponding to the geometric percolation threshold. For $ x_{VL}<x<x_p$, the array behaves as a zero-temperature vortex-glass. Numerical results for $f=1/2$ from defect energy calculations are presented which are consistent with this scenario.