Temperature sensitivity of true random number generation in stochastic magnetic actuated random transducer devices

True random number sources are of great interest for numerous applications such as cryptography and Monte Carlo simulations. Here we show that perpendicularly magnetized magnetic tunnel junctions operated in the ballistic switching limit (ns duration pulses) have great potential for such applications due to the stochasticity of their spin-transfer-torque driven reversal. In the ballistic limit the resulting junction state is random mainly because of the thermal distribution of the initial magnetization state. We denote this a stochastic magnetic actuated random transducer (SMART) device because a pulse activates the junction to generate a random bit, much like a coin flip. We find that the experimentally obtained switching probability characteristics can be well described by a simple macrospin model. We also show that our SMART devices with a thermal stability factor (Δ = 39) operated in the ballistic limit are much less sensitive to temperature variations than the same device operated with longer pulses. In addition, we investigate the stochastic nature of our SMART devices by comparing their statistics to Bernoulli trials and show that we can successfully sample a uniform distribution¹, which is commonly used in computations that require random numbers. Our results demonstrate that SMART devices are a great candidate for true random number generation due to their easily controllable characteristics, while being relatively robust towards environmental changes.



¹ L. Rehm et al., arXiv:2209.01480