2018 Fiscal Year Final Research Report
Microscopic investigation of the mechanism of field-induced reentrant superconductivity in itinerant ferromagnetic superconductors(Fostering Joint International Research)
| Project/Area Number |
15KK0174
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| Research Category |
Fund for the Promotion of Joint International Research (Fostering Joint International Research)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Condensed matter physics II
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| Research Institution | Japan Atomic Energy Agency |
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Principal Investigator |
Tokunaga Yo 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 原子力科学研究所 先端基礎研究センター, 研究主幹 (00354902)
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| Research Collaborator |
HORVATIC Mladen グルノーブル国立強磁場研究所, NMR研究グループ, グループリーダー
Julien Marc
Berthier Claude
Aoki Dai
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| Project Period (FY) |
2016 – 2018
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| Keywords | 強磁性超伝導 / 核磁気共鳴 / 磁場誘起超伝導 / 三重臨界点 / 磁気揺らぎ |
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| Outline of Final Research Achievements |
Ferromagnetic (FM) order is incompatible in general with superconductivity with singlet spin pairs, since a strong exchange eld in FM state forces the spin pairs to align in the same direction. In contrast, fluctuation of FM moments has been supposed to create a binding force between quasiparticles with triplet spin, in the same manner as in the mechanism of super fluid pairing in 3He. Such an unconventional spin-triplet state, mediated by FM fluctuations, is now expected to be realized in a family of uranium based compounds, In this study, we have collaborated with LNCMI-Grenoble in France, and performed NMR studies on a single crystal of uranium based FM superconductor URhGe. Our NMR results provides strong evidence that the pairing mechanism of reentrant superconductivity in URhGe is mediated by spin fluctuations developed around the tricritical point under magnetic fields.
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| Free Research Field |
固体物理
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| Academic Significance and Societal Importance of the Research Achievements |
超伝導はもともと磁場とは相性が悪く、強い磁場をかけていくと最後には超伝導が壊されてしまう。ところがウラン化合物で見つかった強磁性超伝導体では、磁場によって新しい超伝導が誘起される。この特異な振る舞いは、新しい超伝導機構の存在を直感的に示唆している。本国際共同研究では、最先端の高磁場NMR技術を持つフランス国立強磁場研究所と共同で、ウラン系強磁性超伝導体のNMR研究を行い、磁場で誘起されたスピン揺らぎが磁場誘起超伝導の発現に強く関わっていることを明らかにした。今後この磁場で安定化する特異な超伝導機構が解明が進めば、超伝導応用の可能性を大きく広げることになる。
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