Kyu Hyoun Kim, Mingu Kang
ICEIC 2024
We experimentally explore a synthetic-antiferromagnetically (SAF) coupled easy-plane stochastic magnetic tunnel junction (EP-SMTJ) for a baseline device behavior assessment. The tunnel conductance fluctuates over time due to magnetoresistance reflecting the superparamagnetic state of the EP-SMTJ's layers. Binary digitizing at its median gives a stochastic bit stream, which is analyzed using the NIST SP800-22r1a test suite. When the tunnel conductance is sampled at different times for producing the binary bit stream, a best bit rate of ∼250 Mb/s is seen. If two independently taken bit streams are xored, the effective bit rate can be >1 Gb/s, provided that the in-plane anisotropy is small compared to ambient temperature (kBTa). The SAF design for both the free and the reference layer allows for a device conductance fluctuation median that is well centered and only weakly voltage-bias dependent. Comparison of experimental observations with a four-moment coupled finite-temperature macrospin model reveals the role of in-plane anisotropy as causing additional telegraphing fluctuations, which is associated with a longer timescale for stochasticity - a behavior that needs to be optimized for high-speed stochastic bit-stream applications.
Kyu Hyoun Kim, Mingu Kang
ICEIC 2024
Hadjer Benmeziane, Imane Hamzaoui, et al.
IJCAI 2024
Ankur Agrawal, Monodeep Kar, et al.
VLSI Technology 2023
Jonathan Z. Sun
Journal of Applied Physics