Bifurcation structure and chaos in nanomagnet coupled to Josephson junction

TL;DR

This paper investigates the complex bifurcation and chaotic dynamics in a nanomagnet coupled to a Josephson junction, revealing how superconductivity and magnetism interplay to produce diverse magnetic behaviors.

Contribution

It provides a detailed analysis of magnetization bifurcations and chaos in the system, highlighting the effects of external driving and energy ratios, which was not previously explored.

Findings

Multiple precessional motions linked to chaos and bistability.

High-frequency periodic modes and chaos near resonance.

Quasiperiodic behavior observed far from resonance.

Abstract

Recently an irregular easy axis reorientation demonstrating the Kapitza pendulum features were observed in numerical simulations of nanomagnet coupled to the Josephson junction. To explain its origin we study the magnetization bifurcations and chaos which appear in this system due to interplay of superconductivity and magnetism. The bifurcation structure of the magnetization under the variation of Josephson to magnetic energy ratio as a control parameter demonstrates several precessional motions. They are related to chaotic behavior, bistability, and multiperiodic orbits in the ferromagnetic resonance region. Effect of external periodic drive on the bifurcation structure is investigated. The results demonstrate high-frequency modes of periodic motion and chaotic response near resonance. Far from the ferromagnetic resonance we observe a quasiperiodic behavior.