2021 Fiscal Year Final Research Report
Spin fluctuations and superconductivity in iron-based superconductors using pulsed neutrons
| Project/Area Number |
19K03718
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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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| Review Section |
Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
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| Research Institution | Okayama University |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | 超伝導 / 中性子回折 |
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| Outline of Final Research Achievements |
In this project, we used NaAs as a fluxing agent and succeeded in growing single crystals with a size on the order of cm by controlling the flux ratio. This study has increased the crystal size by about 100 times, and has made it possible to perform neutron experiments.
Neutron scattering experiments on Ca0.44Na0.56Fe2As2 (Tc=33.4K) showed many consistent trends, such as magnetic excitation over 200 meV as in the previous work on Ba1-xKxFe2As2, suggesting a correlation between the exchange interaction J and Tc. The dispersion relation of magnetic excitations was also found to have a clear dispersion relation in the L direction This indicates that the strong 3-D correlation remains robust in the Ca system because of its shorter c-axis length compared to that of the Ba system.
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| Free Research Field |
固体物理学
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| Academic Significance and Societal Importance of the Research Achievements |
これまでCa系の単結晶育成の報告はいくつかなされているが、その結晶サイズはミリオーダーと非常に小さく、非弾性中性子散乱実験が困難とされて来た。本研究課題ではNaAsフラックスの比を制御することにより cmオーダーの大きさの単結晶育成を成功させ、中性子実験を実施することを可能にした。
また、中性子実験により明らかにした最適ドープ領域の磁気励起および磁気相図の結果から磁性と超伝導の強い相関関係を示すと共に、キャリアドープにより磁気秩序は抑制されるが最大のTcを示すx=0.56においても非常に微弱であるが磁気散乱が観測され超伝導と磁性の共存が観測された。
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