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Search for novel physical properties in spin-orbit fluctuated systems

Research Project

Project/Area Number 18K03543
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 InstitutionKagoshima University

Principal Investigator

Okuda Tetsuji  鹿児島大学, 理工学域工学系, 准教授 (20347082)

Co-Investigator(Kenkyū-buntansha) 梶本 亮一  国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 J-PARCセンター, 研究主幹 (30391254)
齋藤 智彦  東京理科大学, 理学部第一部応用物理学科, 教授 (30311129)
桑原 英樹  上智大学, 理工学部, 教授 (90306986)
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: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Keywords強相関電子材料 / 二量体 / 電荷整列 / 熱電特性 / 擬ブルッカイト / 強相関電子系 / 擬ブルッカイト型Ti酸化物 / スピン・軌道揺らぎ / 強相関電子系物質 / 希釈磁性半導体 / フラストレート磁性体
Outline of Final Research Achievements

In this project, we searched for novel physical properties in chemically substituted pseudobrookite Ti3O5 with enhanced spin-orbit fluctuations. In the low temperature β phase of Ti3O5, a spin-singlet dimerization between the neighboring Ti3+ ions occurs with accompanying Ti3+/Ti4+ charge ordering. We succeeded in growth of the single crystals mixed with AlTi2O5 having the similar structure and found that the α, λ, and β phases sequentially appeared at room temperature with the change in the Al content and that the correlated conductive state where the dimer correlations strongly remained were realized even in the paramagnetic α and λ phases. Furthermore, we found unique magnetic properties and relatively good high-temperature thermoelectric properties, originating in the fluctuations of dimerization, near the phase boundary between the λ and β phases.

Academic Significance and Societal Importance of the Research Achievements

スピン一重項の二量体形成は一般的な量子現象であり、Ti3O5やTi4O7の低温での二量体形成は古くから知られていた。ところが、Ti3O5のλ相やTi4O7の中間相ではバイポーラ・スピン液体状態や異常コヒーレント状態などが提案されており、それらの磁気・電子状態は未解明のままであった。さらに、近年、理論や実験の進展に伴い、スピン・軌道整列が起源となる多量体形成が多くの物質で見出され、その物性研究が進展しつつある。以上の背景のもと、本課題で育成に成功した元素置換したTi3O5やTi2O3の単結晶での発見は、二量体物性の理解を深化させ、さらに、巨大熱電応答など新量子物性につながる重要なものと思われる。

Report

(2 results)
  • 2020 Final Research Report ( PDF )
  • 2018 Research-status Report
  • Research Products

    (8 results)

All 2019 2018

All Journal Article (2 results) (of which Peer Reviewed: 2 results,  Open Access: 2 results) Presentation (6 results) (of which Int'l Joint Research: 3 results,  Invited: 1 results)

  • [Journal Article] Elastic and dynamical structural properties of La and Mn-doped SrTiO3 studied by neutron scattering and their relation with thermal conductivities2018

    • Author(s)
      Ryoichi Kajimoto, Mitsutaka Nakamura, Naoki Murai, Shin-ichi Shamoto, Takashi Honda, Kazutaka Ikeda, Toshiya Otomo, Hiroto Hata, Takahiro Eto, Masaaki Noda, Hideki Kuwahara, Tetsuji Okuda
    • Journal Title

      Scientific Reports

      Volume: 8 Issue: 1

    • DOI

      10.1038/s41598-018-27984-z

    • Related Report
      2018 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Schottky specific heat of the lightly Mn-substituted electron-doped SrTiO32018

    • Author(s)
      T. Okuda, R. Kajimoto, M. Noda, H. Kuwahara
    • Journal Title

      AIP Advances

      Volume: 8 Issue: 10

    • DOI

      10.1063/1.5042835

    • Related Report
      2018 Research-status Report
    • Peer Reviewed / Open Access
  • [Presentation] Thermoelectric Properties of Pseudobrookite Al1-xTi2+xO5 for 0 ≦ x ≦ 12019

    • Author(s)
      R. Takahama, T. Ishii, T. Okuda
    • Organizer
      THE 19th JAPAN-KOREA-TAIWAN SYMPOSIUM ON STRONGLY CORRELATED ELECTRON SYSTEMS (JKT19)
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research
  • [Presentation] 擬ブルッカイト酸化物Al1-xTi2+xO5の熱電特性2019

    • Author(s)
      高浜隆成, 石井透依, 寺倉千恵子, 竹下直. 十倉好紀, 奥田哲治
    • Organizer
      日本物理学会 第74回年次大会
    • Related Report
      2018 Research-status Report
  • [Presentation] Hole-doping effect on the Néel state of delafossite CuCrO22018

    • Author(s)
      T. Okuda
    • Organizer
      European Materials Research Society (E-MRS) 2018 Fall Meeting
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Schottky specific heat of the lightly Mn-substituted electron-doped SrTiO32018

    • Author(s)
      T. Okuda, R. Kajimoto, M. Noda, H. Kuwahara
    • Organizer
      International Conference on Magnetism (ICM2018)
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research
  • [Presentation] 磁性不純物をドープしたルチル型酸化物TiO2の物性2018

    • Author(s)
      米田智尭, 國守大也, 永田勇平, 奥田哲治
    • Organizer
      第124回 日本物理学会 九州支部例会
    • Related Report
      2018 Research-status Report
  • [Presentation] 擬ブルッカイト型酸化物Al1-xTi2+xO5の物性2018

    • Author(s)
      高浜隆成, 石井透依, 奥田哲治
    • Organizer
      第124回 日本物理学会 九州支部例会
    • Related Report
      2018 Research-status Report

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Published: 2018-04-23   Modified: 2022-12-28  

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