Asymmetric ac fluxon depinning in a Josephson junction array: A highly discrete limit

TL;DR

This paper investigates how topological solitons called fluxons depin and move in a highly discrete Josephson junction array driven by biharmonic ac signals, revealing complex chaotic depinning mechanisms.

Contribution

It provides a detailed analysis of the depinning transition mechanisms, including chaotization pathways, in a strongly discrete Josephson junction array under biharmonic ac driving.

Findings

Depinning occurs via chaotization of fluxon orbits.

Depinning mechanisms include period-doubling and intermittency.

Chaotic depinning depends on driving parameters.

Abstract

Directed motion and depinning of topological solitons in a strongly discrete damped and biharmonically ac-driven array of Josephson junctions is studied. The mechanism of the depinning transition is investigated in detail. We show that the depinning process takes place through chaotization of an initially standing fluxon periodic orbit. Detailed investigation of the Floquet multipliers of these orbits shows that depending on the depinning parameters (either the driving amplitude or the phase shift between harmonics) the chaotization process can take place either along the period-doubling scenario or due to the type-I intermittency.