# Synchrony breakdown and noise-induced oscillation death in ensembles of serially connected spin-torque oscillators

## TL;DR

This paper investigates how collective dynamics in serially connected spin-torque oscillators are affected by proximity to homoclinic bifurcations and how strong common noise can suppress oscillations, providing explicit noise threshold expressions.

## Contribution

It reveals the impact of homoclinic bifurcations on synchronization and derives explicit noise thresholds for oscillation suppression in spin-torque oscillator ensembles.

## Key findings

- Proximity to homoclinic bifurcation hampers synchronization.
- Strong common noise can suppress magnetic precession.
- Explicit noise amplitude threshold for suppression derived.

## Abstract

We consider collective dynamics in the ensemble of serially connected spin-torque oscillators governed by the Landau-Lifshitz-Gilbert-Slonczewski magnetization equation. Proximity to homoclinicity hampers synchronization of spin-torque oscillators: when the synchronous ensemble experiences the homoclinic bifurcation, the Floquet multiplier, responsible for the temporal evolution of small deviations from the ensemble mean, diverges. Depending on the configuration of the contour, sufficiently strong common noise, exemplified by stochastic oscillations of the current through the circuit, may suppress precession of the magnetic field for all oscillators. We derive the explicit expression for the threshold amplitude of noise, enabling this suppression.