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Optical study for electronic state of electron-doped superconducting copper oxides

Research Project

Project/Area Number 18K03513
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
Research InstitutionOsaka University

Principal Investigator

Tajima Setsuko  大阪大学, 理学研究科, 名誉教授 (70188241)

Co-Investigator(Kenkyū-buntansha) 中島 正道  大阪大学, 理学研究科, 助教 (20724347)
Project Period (FY) 2018-04-01 – 2021-03-31
Project Status Completed (Fiscal Year 2020)
Budget Amount *help
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2018: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Keywords強相関電子系 / 銅酸化物超伝導体 / 赤外スペクトル / ラマン散乱スペクトル / 高温超伝導 / 電子相図 / 電子ドープ系銅酸化物 / 赤外活性フォノン / ラマン活性フォノン / 赤外フォノン / 電子ドープ / フォノン / 光学スペクトル
Outline of Final Research Achievements

Recently the electronic phase diagram for electron-doped superconducting cuprates has been reconsidered, although it had been widely accepted for the last 30 years. By measuring far-infrared and Raman scattering spectra, we have examined the presence of oxygen deficiency in two samples, the as-grown crystal and the strongly reduced crystal. For both samples, we observed additional phonon modes that are not expected from the group theory. These are ascribed to the defect-induced modes. However, because these defect-induced modes are commonly observed in both samples, namely, independent of oxygen content, we judged that they are not induced by oxygen deficiency. As a conclusion, we found no evidence for oxygen deficiency in optical spectra. This indicates that the newly proposed phase diagram for the strongly reduced samples is intrinsic for this system.

Academic Significance and Societal Importance of the Research Achievements

モット絶縁体に電子を注入した場合と正孔を注入した場合が同じかどうか、といういわゆる「電子・正孔対称性問題」は、長らく議論されてきた。銅酸化物高温超伝導体が発見されてから約30年、電子注入系と正孔注入系の電子相図は、ほぼ対称と理解されてきた。最近になって、強還元して正しい酸素濃度にした試料では、非常に僅かな正孔注入(場合によっては注入なし)で超伝導になるという電子相図が報告され、その正否が議論されている。本研究で強還元による有為な酸素欠損はないことが示され、僅かな正孔注入で超伝導になるという新しい電子相図が本質的なものであることが支持された。即ち、電子・正孔注入は非対称であることがわかった。

Report

(4 results)
  • 2020 Annual Research Report   Final Research Report ( PDF )
  • 2019 Research-status Report
  • 2018 Research-status Report
  • Research Products

    (3 results)

All 2021 2019

All Presentation (3 results) (of which Int'l Joint Research: 1 results)

  • [Presentation] Bi2223における光学反射率測定2021

    • Author(s)
      伊藤優太、水溜勝也、中島正道、宮坂茂樹、佐々木菜絵、山口隼平、渡辺孝夫、田島節子
    • Organizer
      日本物理学会第76回年次大会
    • Related Report
      2020 Annual Research Report
  • [Presentation] Study of optical properties of triple layer cuprates Bi22232019

    • Author(s)
      Y. Ito, K. Mizutamari, M. Nakajima, S. Miyasaka, N. Sasaki, N. Yamaguchi, T. Watanabe and S. Tjima
    • Organizer
      The 32nd International Symposium on Superconductivity
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research
  • [Presentation] 光学フォノンスペクトルから見る(Pr,La,Ce)2CuO4の還元アニール効果2019

    • Author(s)
      水溜勝也、大西諒太、中島正道、宮坂茂樹、田島節子、洲村拓哉、足立匡
    • Organizer
      日本物理学会第74回年次大会
    • Related Report
      2018 Research-status Report

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Published: 2018-04-23   Modified: 2022-01-27  

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