Synchronization of electrically coupled stochastic magnetic oscillators induced by thermal and electrical noise

TL;DR

This paper demonstrates how two electrically coupled superparamagnetic tunnel junctions can synchronize to a periodic drive under thermal and electrical noise, revealing different behaviors and potential for noise-driven computation.

Contribution

It introduces a combined numerical and analytical study of synchronization in coupled magnetic oscillators influenced by distinct noise sources, highlighting their different effects.

Findings

Thermal noise stabilizes phase-locking with one junction blocked in a state.

Electrical noise induces high correlation and cannot block a junction.

Synchronization can be controlled by tuning thermal and electrical noise levels.

Abstract

Superparamagnetic tunnel junctions are nanostructures that auto-oscillate stochastically under the effect of thermal noise. Recent works showed that despite their stochasticity, such junctions possess a capability to synchronize to subthreshold voltage drives, in a way that can be enhanced or controlled by adding noise. In this work, we investigate a system composed of two electrically coupled junctions, connected in series to a periodic voltage source. We make use of numerical simulations and of an analytical model to demonstrate that both junctions can be phase-locked to the drive, in phase or in anti-phase. This synchronization phenomenon can be controlled by both thermal and electrical noises, although the two types of noises induce qualitatively different behaviors. Namely, thermal noise can stabilize a regime where one junction is phase-locked to the drive voltage while the other is blocked in one state. On the contrary, electrical noise causes the junctions to have highly correlated behaviors and thus cannot induce the latter. These results open the way for the design of superparamagnetic tunnel junctions that can perform computation through synchronization, and which harvest the largest part of their energy consumption from thermal noise.