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Published on: March 24, 2019
Local bifurcation with spin-transfer torque in superparamagnetic tunnel junctions
Takuya Funatsu1, Shun Kanai2,3,4,5, Jun'ichi Ieda6
1Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
Researchers explored the Néel-Arrhenius law in magnetic tunnel junctions using spin-transfer torque. They precisely determined switching rate exponents, advancing probabilistic computing hardware.
Area of Science:
- Physics
- Materials Science
- Computer Engineering
Background:
- Thermally-activated phenomena follow the Arrhenius law, but its application to magnetic tunnel junctions with spin-transfer torque (STT) is debated.
- The exponents in the Néel-Arrhenius law for STT-driven switching have been difficult to measure in conventional nanomagnets.
Purpose of the Study:
- To rigorously investigate the Néel-Arrhenius law in superparamagnetic tunnel junctions under STT.
- To determine the exponents of the thermally-activated switching rate.
- To explore the potential for probabilistic computing hardware.
Main Methods:
- Utilized superparamagnetic tunnel junctions for high sensitivity to perturbations.
- Employed homodyne-detected ferromagnetic resonance.
- Conducted nanosecond STT switching experiments.
- Analyzed random telegraph noise.
Main Results:
- Successfully determined the exponents for the thermally-activated switching rate.
- Demonstrated that results align with the concept of local bifurcation.
- Showcased superparamagnetic tunnel junctions as effective testers for statistical physics.
Conclusions:
- The study provides a rigorous mathematical foundation for understanding STT in magnetic tunnel junctions.
- Superparamagnetic tunnel junctions are valuable for statistical physics research.
- These findings enable sophisticated engineering of probabilistic computing hardware.
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