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.
@article{arxiv.2010.14393,
title = {Demonstration of nanosecond operation in stochastic magnetic tunnel junctions},
author = {Christopher Safranski and Jan Kaiser and Philip Trouilloud and Pouya Hashemi and Guohan Hu and Jonathan Z Sun},
journal= {arXiv preprint arXiv:2010.14393},
year = {2021}
}