| Project/Area Number |
19K15428
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 29010:Applied physical properties-related
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| Research Institution | Tohoku University |
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Principal Investigator |
Kurenkov Aleksandr 東北大学, 先端スピントロニクス研究開発センター, 学術研究員 (80830645)
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| Project Period (FY) |
2019-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2020: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2019: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
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| Keywords | neuromorphic computing / synapse / neuron / spintronics / exchange bias / antiferromagnet / ferromagnet / Spintronics / Spin-orbit torque / Fast switching / Antiferromagnet / Exchange bias / Synapse / Neuron / Neuromorphic / artificial intelligence / antiferromagnets |
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| Outline of Research at the Start |
This research is aimed to using magnetization dynamics for biologically plausible computations in artificial spiking neural networks. Emulation of a synapse and neuron in our research will allow very efficient, enduring, non-volatile architectures without leakage currents and with high frequencies.
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| Outline of Final Research Achievements |
We have clarified the microscopic mechanism behind spin-orbit torque switching in ferromagnet/antiferromagnet (FM/AFM) stacks. It was found that exchange bias (EB) at the FM/AFM interface varies throughout the system and causes non-binary behavior. This variation happens at a fine scale of the stack grain size i.e. ~ 15 nm. Within a grain, the FM/AFM interface can be assumed to be monocrystalline and it can give EB as large as hundreds of mT. Much weaker EB of ~20-40 mT, previously measured at the FM domain level (~ 200 nm in effective diameter) can be explained by averaging effects. EB in each site is determined by crystallographic orientation of the grain and the quality of the FM/AFM interface, which leads to a wide dispersion of values in polycrystalline non-epitaxial systems.
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| Academic Significance and Societal Importance of the Research Achievements |
The new picture of EB in polycrystalline systems, confirmed experimentally and with simulations, is crucial for understanding and engineering of EB both for fundamental studies and neuromorphic applications.
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