| Project/Area Number |
15KK0160
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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 | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2016 – 2019
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥14,300,000 (Direct Cost: ¥11,000,000、Indirect Cost: ¥3,300,000)
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| Keywords | 超シャロウバンド / 鉄系超伝導 / BCS-BECクロスオーバー / ネマティック量子臨界点 / 新奇超伝導相 / 軌道選択 / FFLO状態 / 熱輸送測定 / 強磁場測定 / 低温高磁場相 / 熱伝導率 / 超伝導ギャップ構造 / ネマティシティ / 準粒子励起 / 強相関電子系 / 非従来型超伝導 / ネマティック転移 |
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| Outline of Final Research Achievements |
The superconducting semimetal FeSe has been found to be deep inside the BCS-BEC crossover regime. In this work, a team of scientists has investigated heat transports in FeSe in intensive fields up to 35 T and found compelling evidence of a distinct high-field superconducting phase which is separated from the usual superconducting phase via a first-order phase transition. This high-field phase is attributed to an exotic state, the so-called FFLO phase, first predicted in 1964. In the isovalently substituted FeSe1-xSx superconductors, the team found non-Fermi liquid charge transports in the vicinity of a novel type of quantum critical point (QCP) of pure nematic order without accompanying other orders. The set of anomalous charge transport properties show striking resemblance to those reported in high-Tc cuprates and heavy Fermion superconductors. A common set of anomalous charge transport properties captures a universal feature of the non-Fermi liquid transport properties near the QCP.
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| Academic Significance and Societal Importance of the Research Achievements |
これまでヘリウム3温度域において18Tを超える極限環境での熱伝導率の精密測定を行える環境は世界にもなかった。本研究では、世界屈指の強磁場施設の一つであるナイメーヘン強磁場研究所においてヘリウム3温度域、最大35テスラまでの強磁場熱伝導率測定を確立し、新奇な超伝導状態の探索と解明を可能とした。これは本研究で対象とした研究に留まらず、様々な系において未踏の実験を可能とした意義深いものといえる。
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