2023 Fiscal Year Final Research Report
Magnetic structure of superconductor/ferromagnet composites with fractal structure
| Project/Area Number |
21H01622
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 26020:Inorganic materials and properties-related
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| Research Institution | Kobe University |
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Principal Investigator |
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | 超伝導近接効果 / 放電プラズマ焼結 / フラクタル / ジョセフソン接合 |
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| Outline of Final Research Achievements |
We investigated vortex matter in a proximity-coupled Mg/MgO/MgB2 nanocomposite with ~30 vol. % of MgB2 using magneto-optical imaging, scanning superconducting quantum interface device microscopy, and pinning force analysis. This nanocomposite was prepared by spark plasma sintering (SPS) of the MgO/MgO/MgB2 mixture powders obtained from a solid phase reaction between Mg and B2O3. The resulting nanocomposite is characterized by scale-free distributions of MgB2 components and the atomically clean MgO/MgB2 interfaces. It is also found that high SPS temperature is the key to improve the proximity-induced superconducting properties of the Mg/MgO/MgB2 nanocomposite. This proximity-coupled system acts as a fully phase coherent superconductor with isotropic pinning and strong superfluid phase stiffness irrespective of the low volume fraction of MgB2.
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| Free Research Field |
無機材料科学
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| Academic Significance and Societal Importance of the Research Achievements |
原子レベルでクリーンな界面を有するS/N/S接合は, 長距離に及ぶ近接効果や, 量子磁束の形成という観点から, 超伝導が寄与する新たな量子効果の発現の場として興味深い実験系を提供する。しかし, これまでの報告はTcが数K以下の金属を用いた薄膜に限られていた。本研究で用いた試料は，バルク状のMg / MgO / MgB2フラクタルナノ複合体であるため，バルク超伝導体の基礎的物性の測定が可能となる。本研究成果は，超伝導近接効果に関する新しい学術的知見を与えるだけでなく，次世代の超伝導デバイス創成に向けた基盤的知識を与えるものである。
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