Phase Transition and Critical Dynamics in Diluted Josephson Junction Arrays

TL;DR

This study investigates how percolative disorder affects phase transitions and vortex dynamics in diluted Josephson-junction arrays, revealing the suppression of the KT transition and the persistence of critical dynamics due to fractal structures.

Contribution

It demonstrates that percolative disorder eliminates the KT transition in 2D XY systems and uncovers persistent critical dynamics linked to fractal geometry near the percolation threshold.

Findings

KT transition is eliminated by disorder below percolation threshold

Superconductivity persists at low temperatures despite loss of KT order

Critical dynamics continue down to zero temperature near percolation threshold

Abstract

Measurements of the $IV$ characteristics of site-diluted Josephson-junction arrays have revealed intriguing effects of percolative disorder on the phase transition and the vortex dynamics in a two-dimensional XY system. Different from other types of phase transitions, the Kosterlitz-Thouless (KT) transition was eliminated with the introduction of percolative disorder far below the percolation threshold. Even after the KT order had been removed, the system remained superconducting at low temperatures by establishing a different type of order. Near the percolation threshold, evidence was found that, as a consequence of the underlying fractal structure, the critical dynamics of the phase degrees of freedom persisted down to zero temperature.