Controlling the phase locking of unstable magnetic bits for ultra-low power computation

TL;DR

This paper demonstrates that superparamagnetic tunnel junctions can be synchronized using electrical noise, enabling ultra-low power computation with minimal energy consumption, despite their inherent stochastic behavior.

Contribution

It introduces a method to control phase locking in superparamagnetic nanomagnets via electrical noise, paving the way for ultra-low power oscillator-based computing.

Findings

Phase locking can be induced and suppressed by electrical noise.

Synchronization conditions are modeled and predicted.

Total energy cost for synchronization is below 10^-13 Joules.

Abstract

When fabricating magnetic memories, one of the main challenges is to maintain the bit stability while downscaling. Indeed, for magnetic volumes of a few thousand nm3, the energy barrier between magnetic configurations becomes comparable to the thermal energy at room temperature. Then, switches of the magnetization spontaneously occur. These volatile, superparamagnetic nanomagnets are generally considered useless. But what if we could use them as low power computational building blocks? Remarkably, they can oscillate without the need of any external dc drive, and despite their stochastic nature, they can beat in unison with an external periodic signal. Here we show that the phase locking of superparamagnetic tunnel junctions can be induced and suppressed by electrical noise injection. We develop a comprehensive model giving the conditions for synchronization, and predict that it can be achieved with a total energy cost lower than 10-^13 J. Our results open the path to ultra-low power computation based on the controlled synchronization of oscillators.