2022 Fiscal Year Final Research Report
Charge-fluctuation mechansim of high-temperature superconductivity in cuprates using resonant inelastic x-ray scattering
| Project/Area Number |
19K03741
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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 | The University of Tokyo (2022)
Waseda University (2019-2021) |
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Principal Investigator |
Fujimori Atsushi 東京大学, 大学院理学系研究科(理学部), 名誉教授 (10209108)
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| Co-Investigator(Kenkyū-buntansha) |
溝川 貴司 早稲田大学, 理工学術院, 教授 (90251397)
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| Project Period (FY) |
2019-04-01 – 2023-03-31
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| Keywords | 高温超伝導体 / 共鳴軟X線非弾性散乱 / 角度分解光電子分光 |
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| Outline of Final Research Achievements |
Charge order, charge excitation, and phonon anomalies in cuprate high-temperature superconductors were studied by resonant inelastic x-ray scattering, and new insights into the superconductivity mechanism and the nature of the enigmatic pseudogap were obtained. Critical charge fluctuations and phonon anomalies associated with the quantum phase transition between the pseudogap phase and the Fermi-liquid phase were identified in the low-energy region near the charge-order peak. At higher energies, spectral changes in the exciton peak between the pseudogap phase and the superconducting phase were observed as predicted by the excitonic charge-fluctuation mechanism of superconductivity. At even higher energies, “acoustic plasmon”, a collective charge excitation of two-dimensional electron system was first observed in hole-doped cuprates. Using angle-resolved photoemission spectroscopy, a nematic electronic structure was identified in the pseudogap phase.
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| Free Research Field |
物性物理実験
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| Academic Significance and Societal Importance of the Research Achievements |
発見から35年間の膨大な研究努力にもかかわらず未解決である銅酸化物高温超伝導体の超伝導発現機構と擬ギャップ形成機構を、従来主流であったスピン自由度に注目した研究から視点を変え、電荷ゆらぎに注目して解明を目指し成果を挙げた。実験手法として既に確立している角度分解光電子分光に加えて、新しい手法である共鳴非弾性X線散乱を高い分解能で利用し、電荷秩序、電荷励起、フォノン異常について新しい知見を得ることによって、電荷ゆらぎによる高温超伝導発現機構と擬ギャップ形成機構の確立に大きく近付いた。
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