Safranski Christopher, Kaiser Jan, Trouilloud Philip, Hashemi Pouya, Hu Guohan, Sun Jonathan Z
IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States.
Nano Lett. 2021 Mar 10;21(5):2040-2045. doi: 10.1021/acs.nanolett.0c04652. Epub 2021 Feb 25.
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 a 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 a signal.
在超顺磁状态下工作的磁性隧道结是概率计算领域中很有前景的器件，适用于高维优化或采样问题等应用。此外，随机数生成在密码学领域也备受关注。对于此类应用，器件的不相关波动时间尺度可以决定有效系统速度。从理论上提出，设计为仅具有易平面各向异性的磁性隧道结可提供由其易平面各向异性场决定的波动速率，并且可以在纳秒或更快的时间尺度上运行，这通过其磁阻的时间自相关来衡量。在此，我们提供了圆形易平面磁性隧道结中纳秒级波动的实验证据，这与有限温度耦合宏观自旋模拟结果以及先前的理论预期一致。我们进一步评估了此类信号的随机性程度。
