| Project/Area Number |
16K05444
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | Kyoto University |
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Principal Investigator |
Ikeda Ryusuke 京都大学, 理学研究科, 准教授 (60221751)
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| Project Period (FY) |
2016-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2019: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2016: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
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| Keywords | 超伝導 / パウリ常磁性 / 臨界揺らぎ / 渦糸状態 / 超伝導揺らぎ / 鉄系超伝導 / 渦糸グラス / 鉄系超伝導体 / 重い電子系超伝導 / 反強磁性 / BCS-BECクロスオーバー / 物性理論 / 量子凝縮相 / 常磁性 |
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| Outline of Final Research Achievements |
In an iron-based superconductor FeSe, the density of the conduction electrons is quite low, and the attractive interaction between the electrons leading to the electron-pair condensate and forming a superconductivity is unusually strong. Consequently, it is considered that the superconductivity occurring in this material cannot be described by the conventional theory describing superconducting properties in most of the materials discovered so far. In fact, two strange observations, a high field superconducting phase suggestive of the presence of a strong Pauli paramagnetism (or Zeeman effect) and a unusually broad fluctuation region at higher temperatures than the superconducting transition line in weak magnetic fields have been found there. In the present research, a theory is developed to explain the unusually strong fluctuation effect by extending the conventional superconducting fluctuation theory, and main experimental results in FeSe in maghetic fields have been explained.
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| Academic Significance and Societal Importance of the Research Achievements |
超伝導の理論は、90年代に集中的に研究された銅酸化物高温超伝導も含む多くの超伝導の物理現象を説明できるBCS理論にこれまで基づいてきたが、近年発見され現在盛んに研究されている鉄系超伝導体の一つである FeSe では、BCS理論の枠を超えた引力の強い超伝導が実現しているため、この系を主たる対象とした研究により、超伝導理論を拡張し、その結果を実験事実との比較により検証し、量子凝縮系物理の更なる発展に寄与することができると期待される。
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