핵심 개념
The proposed double-free-layer stochastic magnetic tunnel junctions (sMTJs) with synthetic antiferromagnets (SAFs) can satisfy the key requirements for probabilistic bits (p-bits) - bias independence, uniform randomness, and fast fluctuations without external magnetic fields.
초록
The authors propose a new design for stochastic magnetic tunnel junctions (sMTJs) using double-free-layer structures with synthetic antiferromagnets (SAFs). This design aims to address the limitations of previous sMTJ designs in achieving the ideal characteristics necessary for probabilistic bits (p-bits).
The key insights are:
- Using SAF free layers reduces the dipolar coupling between the free layers, allowing for uncorrelated fluctuations at larger diameters (up to ~100 nm) if the magnets can be made thin enough (≈1-2 nm).
- The double-free-layer structure retains bias-independence and the circular nature of the nanomagnets provides near-uniform randomness with fast fluctuations.
- Theoretical analysis and numerical simulations show that the proposed sMTJ design satisfies the key requirements for p-bits - bias independence, uniform randomness, and fast fluctuations without external magnetic fields.
- Integrating the sMTJ model with advanced transistor models, the authors estimate an energy consumption of ≈3.6 fJ per random bit generation and fluctuation rates of ≈3.3 GHz per p-bit.
- The results provide guidance for the experimental development of superior sMTJs for large-scale and energy-efficient probabilistic computing, with applications in machine learning and artificial intelligence.
통계
The energy to generate a random bit is estimated to be ≈3.6 fJ.
The fluctuation rate is estimated to be ≈3.3 GHz per p-bit.
인용구
"Ideally, the sMTJs should have (a) voltage bias independence preventing read disturbance (b) uniform randomness in the magnetization angle between the free layers, and (c) fast fluctuations without requiring external magnetic fields while being robust to magnetic field perturbations."
"Combining our full sMTJ model with advanced transistor models, we estimate the energy to generate a random bit as ≈3.6 fJ, with fluctuation rates of ≈3.3 GHz per p-bit."