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Superconductivity of SrTiO3 near a non-magnetic quantum critical point

Research Project

Project/Area Number 19H01844
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Review Section Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
Research InstitutionNational Institute of Advanced Industrial Science and Technology

Principal Investigator

Tomioka Yasuhide  国立研究開発法人産業技術総合研究所, エレクトロニクス・製造領域, 上級主任研究員 (60357572)

Project Period (FY) 2019-04-01 – 2022-03-31
Project Status Completed (Fiscal Year 2021)
Budget Amount *help
¥17,420,000 (Direct Cost: ¥13,400,000、Indirect Cost: ¥4,020,000)
Fiscal Year 2021: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2020: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2019: ¥7,280,000 (Direct Cost: ¥5,600,000、Indirect Cost: ¥1,680,000)
Keywords超伝導 / 強誘電体 / 量子臨界点 / チタン酸ストロンチウム / 酸素同位体置換 / 量子常誘電 / 強誘電
Outline of Research at the Start

希薄な電子ドープによって現れる SrTiO3 の超伝導は、従来、試料中に酸素欠損δを生成させ電子ドープを施す (SrTiO3-δ) ことによって研究されてきた。本研究では、Srを希土類イオンで置換した Sr1-xRExTiO3 (RE = La, Pr, Nd,...)、Ti をNb 等で置換した SrTi1-xMxO3 (M = Nb, Ta, and Mo) を対象とし、大型単結晶の育成を始め、酸素同位体置換によって、(強誘電性)量子臨界点近傍での強誘電ゆらぎを制御し、強誘電ゆらぎと超伝導の関係を明らかにする。SrTiO3-δでは見えなかった、超伝導に与える強誘電性の影響に踏み込んでいく。

Outline of Final Research Achievements

Different-type of ferroelectrics, Sr1-yCayTiO3 [TC(FE) = 25 K] and Sr1-yBayTiO3 [TC(FE) = 50 K], show superconductivity by the systematic substitution of Nb5+ for Ti4+ for the electron doping. The two polar metals commonly exhibit a simple superconducting dome with a single convex on top, like Sr1-xLaxTiO3 and SrTi1-xNbxO3. The superconducting transition temperature Tc is enhanced in both polar metals compared with non-polar SrTi1-xNbxO3. Moreover, the maximum Tc reaches 0.75 K, the highest in the families of SrTiO3 ever reported. Interestingly, the Tc enhancement is low in the vicinity of the ferroelectric quantum critical point but becomes much more prominent by further going into the polar region. The results suggest that the dominance of the inversion symmetry breaking may enhance the superconductivity rather than the actively discussed quantum fluctuation around the ferroelectric quantum critical point.

Academic Significance and Societal Importance of the Research Achievements

SrTiO3系の超伝導転移温度 Tc は、従来約 0.3 K であったが、元素置換によって強誘電を生成させると、Tc が大きく上昇し、0.75 K に達することを見出した。これまで、微量な酸素欠損の導入による電子ドーピング等、乱れの導入を最小限に抑える手法が重要視されてきたが、本研究では、対照的に、Sr/Ti それぞれのサイトに元素置換を施す方法を採用して、強誘電キュリー温度/キャリア濃度それぞれを制御し、強誘電/超伝導の相互関係を系統的に探索した。本研究により、本系の超伝導は、強誘電の導入によって増強されることが明らかとなり、本系の超伝導のメカニズム解明に大きな貢献をもたらすと考えられる。

Report

(4 results)
  • 2021 Annual Research Report   Final Research Report ( PDF )
  • 2020 Annual Research Report
  • 2019 Annual Research Report
  • Research Products

    (6 results)

All 2022 2021 2020 2019

All Journal Article (4 results) (of which Peer Reviewed: 4 results,  Open Access: 4 results) Presentation (2 results) (of which Int'l Joint Research: 1 results,  Invited: 1 results)

  • [Journal Article] Elastic study of electric quadrupolar correlation in the paramagnetic state of the frustrated quantum magnet Tb2+δTi2-δO72022

    • Author(s)
      Nii Y.、Hirokane Y.、Nakamura S.、Kabeya N.、Kimura S.、Tomioka Y.、Nojima T.、Onose Y.
    • Journal Title

      Physical Review B

      Volume: 105 Issue: 9 Pages: 094414-094414

    • DOI

      10.1103/physrevb.105.094414

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Kinetic pathway facilitated by a phase competition to achieve a metastable electronic phase2021

    • Author(s)
      Matsuura Keisuke、Oike Hiroshi、Kocsis Vilmos、Sato Takuro、Tomioka Yasuhide、Kaneko Yoshio、Nakamura Masao、Taguchi Yasujiro、Kawasaki Masashi、Tokura Yoshinori、Kagawa Fumitaka
    • Journal Title

      Physical Review B

      Volume: 103 Issue: 4

    • DOI

      10.1103/physrevb.103.l041106

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Magnetic and Electronic Properties of Single Crystals of Perovskite Nickelate Oxide LaNiO3 Prepared by the Laser Diode Floating Zone Method2021

    • Author(s)
      Tomioka Yasuhide、Ito Toshimitsu、Maruyama Erika、Kimura Shinji、Shindo Isamu
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 90 Issue: 3 Pages: 034704-034704

    • DOI

      10.7566/jpsj.90.034704

    • NAID

      210000158839

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Superconductivity near a Ferroelectric Quantum Critical Point in La-doped SrTiO32020

    • Author(s)
      Tomioka Yasuhide、Shirakawa Naoki、Shibuya Keisuke、Inoue Isao H.
    • Journal Title

      JPS Conf. Proc.

      Volume: 30 Pages: 011036-011036

    • DOI

      10.7566/jpscp.30.011036

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Open Access
  • [Presentation] 電荷秩序状態におけるPr0.6Ca0.4MnO3の高次高調波発生2021

    • Author(s)
      中野愛子,内田健人,富岡泰秀,沖本洋一,田中耕一郎
    • Organizer
      日本物理学会
    • Related Report
      2021 Annual Research Report
  • [Presentation] Superconductivity near a Ferroelectric Quantum Critical Point in La-doped SrTiO32019

    • Author(s)
      Y. Tomioka, N. Shirakawa, K. Shibuya, and I. H. Inoue
    • Organizer
      International Conference on Strongly Correlated Electron Systems (SCES2019) (Okayama Convention Center, Okayama, Japan, Sep. 23-28, 2019)
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research / Invited

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Published: 2019-04-18   Modified: 2023-01-30  

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