Regular Article

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

¹ Institute of Physics, Humboldt University of Berlin, Berlin, Germany
² Department of Control Theory, Lobachevsky University Nizhni Novgorod, Nizhnij Novgorod, Russia
³ Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany

^a e-mail: zaks@physik.hu-berlin.de

Received: 15 March 2019
Received in final form: 14 May 2019
Published online: 22 July 2019

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 growth rate per oscillation 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.