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valence quantum criticality investigated by microscopic probes

Research Project

Project/Area Number 19K23417
Research Category

Grant-in-Aid for Research Activity Start-up

Allocation TypeMulti-year Fund
Review Section 0202:Condensed matter physics, plasma science, nuclear engineering, earth resources engineering, energy engineering, and related fields
Research InstitutionTohoku University

Principal Investigator

Taniguchi Takanori  東北大学, 金属材料研究所, 助教 (70849950)

Project Period (FY) 2019-08-30 – 2022-03-31
Project Status Completed (Fiscal Year 2021)
Budget Amount *help
¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Keywords強相関電子系 / 量子臨界現象 / Yb化合物 / ミュオンスピン緩和 / 中性子散乱 / 重い電子系 / 放射光 / 核磁気共鳴 / ミュウオンスピン緩和 / NMR / イッテルビウム
Outline of Research at the Start

これまでスピン自由度が主流であった量子相転移の研究において、“価数”が新しい自由度として注目を集めている。本研究では、申請者が行ったNQR/NMR実験から、価数に由来する量子臨界性の兆候を見出したYbCu4Niを対象に、(1) muSRとNMRによるスピン緩和率の測定から量子臨界現象を確定し、(2) この臨界性が価数に起因することをX線吸収発光分光測定で直接決定する。さらに、(3)中性子散乱を行い、Ybイオンに関する微視的な磁気情報を取得する。これらにより価数に由来した量子臨界現象の存在を決定し、その性質を微視的に明らかにする。

Outline of Final Research Achievements

We focus on the candidate material YnCu4T (T = Ni, Au) with a quantum critical point derived from the valence, and have investigated the electronic properties through some experiments such as single crystal growth, basic physical properties, and muon spin relaxation method and neutron diffraction. At first, we succeeded in synthesizing large single crystals. Using this single crystal sample, a muon spin relaxation experiment was performed at the Rutherford Appleton Laboratory (ISIS) in the United Kingdom. It was clarified that the electronic state changed at the Kondo temperature in YbCu4Au, and the temperature dependence of the electrical resistance can be explained by this result. In addition, the crystal structures of YbCu4Ni and YbCu4Au were confirmed by neutron diffraction experiments at J-PARC (JRR-3), and some changes in the previously proposed crystal structures were found. These results are the basic information for considering valence quantum critical phenomena.

Academic Significance and Societal Importance of the Research Achievements

銅酸化物高温超伝導体や重い電子超伝導体に代表される超伝導について、多くは反強磁性スピン揺らぎの枠組みで量子臨界現象として説明されていることが多い。最近では、多極子揺らぎや強磁性揺らぎに起因する量子臨界現象の存在が指摘されており、新奇な物性探索のために盛んに研究がなされている。本研究では、電子の特徴の一つである価数に注目し、価数揺らぎと量子臨界現象の関係について調べた。そのため、まずは候補物質について単結晶合成を試み、大型のものを得ることに成功した。この成果により、多くの実験プローブを用いることにより、候補物質が示す量子臨界現象の起源を明らかにする基盤が確立した。

Report

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

    (10 results)

All 2022 2021 2020 2019

All Journal Article (3 results) (of which Peer Reviewed: 3 results,  Open Access: 1 results) Presentation (7 results) (of which Int'l Joint Research: 3 results,  Invited: 1 results)

  • [Journal Article] Magnetic refrigeration down to 0.2 K by heavy fermion metal YbCu4Ni2022

    • Author(s)
      Shimura Yasuyuki、Watanabe Kanta、Taniguchi Takanori、Osato Kotaro、Yamamoto Rikako、Kusanose Yuka、Umeo Kazunori、Fujita Masaki、Onimaru Takahiro、Takabatake Toshiro
    • Journal Title

      Journal of Applied Physics

      Volume: 131 Issue: 1 Pages: 013903-013903

    • DOI

      10.1063/5.0064355

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Ultralow temperature NMR of CeCoIn52020

    • Author(s)
      Yamashita M.、Tashiro M.、Saiki K.、Yamada S.、Akazawa M.、Shimozawa M.、Taniguchi T.、Takeda H.、Takigawa M.、Shishido H.
    • Journal Title

      Physical Review B

      Volume: 102 Issue: 16 Pages: 165154-165154

    • DOI

      10.1103/physrevb.102.165154

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Journal Article] Search for the Field-induced Magnetic Instability around the Upper Critical Field of Superconductivity in \(H\parallel c\) in CeCoIn52020

    • Author(s)
      Taniguchi Takanori、Kitagawa Shunsaku、Manago Masahiro、Nakamine Genki、Ishida Kenji、Shishido Hiroaki
    • Journal Title

      JPS Conference Proceedings

      Volume: 30 Pages: 011107-011107

    • DOI

      10.7566/jpscp.30.011107

    • Related Report
      2019 Research-status Report
    • Peer Reviewed / Open Access
  • [Presentation] Magnetic properties of Yb141 system investigated by mu+SR2021

    • Author(s)
      Takanori Taniguchi, Koutaro Osato, Yusuke Nambu, Yoichi Ikeda, Jun Gouchi, Yoshiya Uwatoko, Shunichiro Kittaka, Toshiro Sakakibara, Dita Puspita Sari, Isao Watanabe, Akihiro Koda, Masaki Fujita
    • Organizer
      Materials Research Meetings
    • Related Report
      2021 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 重い電子系金属間化合物YbCu4Niを用いた0.2 Kまでの磁気冷凍の実証2021

    • Author(s)
      志村 恭通, 渡邉 寛大, 谷口 貴紀, 大里 耕太郎, 藤田 全基, 西原 壱政, 山本 理香子, 草ノ瀬 優香, 梅尾 和則, 鬼丸 孝博
    • Organizer
      日本物理学会
    • Related Report
      2020 Research-status Report
  • [Presentation] 重い電子化合物YbCu4Auの単結晶育成とその基礎物性2021

    • Author(s)
      谷口 貴紀, 大里 耕太郎, 池田 陽一, 南部 雄亮, 藤田 全基, 馬 翰明, 郷地 順, 上床 美也, 橘高 俊一郎, 榊原 俊郎
    • Organizer
      日本物理学会
    • Related Report
      2020 Research-status Report
  • [Presentation] Field-Induced Switching of Ferro-Quadrupole Order Parameter in PrTi2Al202020

    • Author(s)
      Takanori Taniguchi, Kazumasa Hattori, Makoto Yoshida, Hikaru Takeda, Shota Nakamura, Toshirou Sakakibara, Masaki Tsujimoto, Akito Sakai, Yousuke Matsumoto, Satoru Nakatsuji, and Masashi Takigawa
    • Organizer
      The 60th REIMEI International Workshop "New excitations for spintronics seen with quantum beams"
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] The La-NMR study of annealed effects in T*-structured La1-x/2Eu1-x/2SrxCuO42019

    • Author(s)
      Takanori Taniguchi, Shunsaku Kitagawa, Kenji Ishida, Shun Asano, Takeshi Noji, Masaki Fujita
    • Organizer
      SMS2019 & GIMRT User Meeting 2019
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research
  • [Presentation] La-NMRによるT*構造La1-x/2Eu1-x/2SrxCuO4の磁性に関する研究2019

    • Author(s)
      谷口貴紀, 北川俊作, 石田憲二,浅野駿, 野地尚, 藤田全基
    • Organizer
      日本物理学会 (2019年秋季大会)
    • Related Report
      2019 Research-status Report
  • [Presentation] 新奇重い電子化合物YbCu4NiのCu-NMR/NQRによる研究2019

    • Author(s)
      谷口貴紀, 北川俊作, 石田憲二, Julián G. Sereni, Mauro Giovannini
    • Organizer
      日本物理学会 (2019年秋季大会)
    • Related Report
      2019 Research-status Report

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Published: 2019-09-03   Modified: 2023-01-30  

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