2D-3D Vortex Line Transition in Two-Layer Josephson Arrays

TL;DR

This paper investigates how vortex lines in two-layer Josephson arrays transition from flux lines to independent pancakes under various conditions, providing insights relevant to high-temperature superconductor experiments.

Contribution

It introduces a calculation of the dynamical response of two-layer Josephson arrays to bias currents, revealing the conditions for vortex line breakup and their implications.

Findings

Vortex lines can break into independent pancakes at high currents or weak coupling.

The response depends on the interlayer coupling strength and magnetic field.

Results are relevant to flux transformer experiments in high-Tc superconductors.

Abstract

We calculate the dynamical response of two-layer Josephson arrays to a bias current applied into only one layer (primary layer), in a perpendicular magnetic field. The pancake vortices in the two layers sometimes form into flux lines which move as a unit under the influence of the bias current. The lines break apart into independent pancakes in sufficiently high currents, sufficiently weak interlayer coupling, or possibly sufficiently high fields. We discuss the relevance of these results to recent experiments in high-T$_c$ superconductors in the flux transformer geometry.