Demonstration of nanosecond operation in stochastic magnetic tunnel junctions

TL;DR

This paper demonstrates that easy-plane magnetic tunnel junctions can operate with nanosecond-scale fluctuations, making them promising for probabilistic computing and cryptography, supported by experimental and simulation evidence.

Contribution

It provides the first experimental validation of nanosecond fluctuations in easy-plane magnetic tunnel junctions, confirming theoretical predictions.

Findings

Nanosecond fluctuation timescales observed experimentally.

Fluctuation behavior consistent with macrospin simulations.

Potential applications in probabilistic computing and cryptography.

Abstract

Magnetic tunnel junctions operating in the superparamagnetic regime are promising devices in the field of probabilistic computing, which is suitable for applications like high-dimensional optimization or sampling problems. Further, random number generation is of interest in the field of cryptography. For such applications, a device's uncorrelated fluctuation time-scale can determine the effective system speed. It has been theoretically proposed that a magnetic tunnel junction designed to have only easy-plane anisotropy provides fluctuation rates determined by its easy-plane anisotropy field, and can perform on nanosecond or faster time-scale as measured by its magnetoresistance's autocorrelation in time. Here we provide experimental evidence of nanosecond scale fluctuations in a circular shaped easy-plane magnetic tunnel junction, consistent with finite-temperature coupled macrospin simulation results and prior theoretical expectations. We further assess the degree of stochasticity of such signal.