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2020 Fiscal Year Annual Research Report

スピン三重項状態を持つ強磁性超伝導体のトポロジカル物性とフェルミ面

Research Project

Project/Area Number 19H00646
Research InstitutionTohoku University

Principal Investigator

青木 大  東北大学, 金属材料研究所, 教授 (30359541)

Co-Investigator(Kenkyū-buntansha) 本多 史憲  東北大学, 金属材料研究所, 准教授 (90391268)
仲村 愛  東北大学, 金属材料研究所, 助教 (30756771)
清水 悠晴  東北大学, 金属材料研究所, 助教 (90751115)
Project Period (FY) 2019-04-01 – 2023-03-31
Keywords強磁性 / 超伝導 / トポロジー / フェルミ面
Outline of Annual Research Achievements

ウラン化合物はスピン軌道結合が大きく、遍歴・局在の中間的な性質を持つ5f電子のために多彩で魅力的な物性が知られている。とくに強磁性超伝導体UGe2, URhGe, UCoGeは強磁性スピンゆらぎによってスピン三重項超伝導が実現しており、磁場誘起(強化)型超伝導を示すなどその特徴は際立っている。本研究はの目的は、強磁性量子臨界終点近傍において、これまで理解されてこなかった電子系における対称性の破れを、リフシッツ転移、ネマティッ ク状態、ポメランチュク不安定性をキーワードに、量子振動効果によるフェルミ面観測から明らかにすることである。さらに、スピン三重項超伝導が実現しているこれらの物質で、トポロジカル超伝導というあらたな視点に基づいた超伝導研究を行うことである。
当該年度は、強磁性超伝導体と同様に、磁場再突入型超伝導など、特徴ある超伝導を示すUTe2の研究が大きく進展した。UTe2は、常磁性の重い電子系超伝導体として2018年末に発見された新しい超伝導体である。強磁性超伝導との比較により、強磁性磁気秩序寸前の物質と当初考えられてきたが、強磁性ゆらぎは実験的に確立していない。その一方で、反強磁性の磁気励起が非弾性中性子散乱により、見出されている。強磁性、反強磁性、価数などの多彩なゆらぎが組み合わさって超伝導を生み出していると考えられる。
UTe2について多くの重要な成果が論文として発表されたが、その中でも最も顕著な成果は圧力下、磁場中の多重超伝導相の発見である。0.3GPaのわずかな圧力で、超伝導転移温度は分裂する。その圧力で、磁場を磁化容易軸方向に加えると、上部臨界磁場が低温で急激に上昇することを見出した。これが、分裂した下部の超伝導転移温度から伸びており、多重超伝導相を形成していることを交流比熱測定から明らかにした。スピン、軌道の自由度を持つ、スピン三重項超伝導の特徴を捉えた。

Current Status of Research Progress
Current Status of Research Progress

1: Research has progressed more than it was originally planned.

Reason

当初予想していなかったUTe2の多重超伝導が熱力学的な物理量で明瞭に観測されたことは、大きな成果である。成果をまとめた論文は、注目論文として取り上げられ、プレス発表も行われた。純良単結晶が得られたことが重要なポイントである。また、これまでの極限環境下の実験技術の蓄積により、高精度の実験が行われたことも大きい。さらに、この研究は、フランスのCEA-Grenobleの研究者らと国際共同研究として進めている。国内外の共同研究者の総力を結集した研究である。多重超伝導の実験結果が明らかになったことにより、複数の理論グループからモデル計算が行われ、超伝導秩序パラメーターの違いとして説明がなされるなど、この分野の研究のさらなる発展につながっている。

Strategy for Future Research Activity

UTe2の純良単結晶育成と高圧下の物性測定をさらに進める。超伝導が破壊される臨界圧力は1.5GPaと低いために、ピストンシリンダー型圧力セルによるさまざまな実験が可能である。臨界圧を超えた磁気相の同定も行う。また、臨界圧近傍で強磁場を加えることで、新奇な物理現象の探索を行う。純良単結晶育成の最適化を図り、ドハース・ファンアルフェン効果によるフェルミ面の観測を目指す。

  • Research Products

    (37 results)

All 2021 2020 Other

All Int'l Joint Research (1 results) Journal Article (24 results) (of which Int'l Joint Research: 20 results,  Peer Reviewed: 24 results,  Open Access: 7 results) Presentation (12 results) (of which Int'l Joint Research: 8 results,  Invited: 7 results)

  • [Int'l Joint Research] CEA-Grenoble/LNCMI(フランス)

    • Country Name
      FRANCE
    • Counterpart Institution
      CEA-Grenoble/LNCMI
  • [Journal Article] Fermi-Surface Instability in the Heavy-Fermion Superconductor UTe22020

    • Author(s)
      Niu Q.、Knebel G.、Braithwaite D.、Aoki D.、Lapertot G.、Seyfarth G.、Brison J-P.、Flouquet J.、Pourret A.
    • Journal Title

      Physical Review Letters

      Volume: 124 Pages: 086601

    • DOI

      10.1103/PHYSREVLETT.124.086601

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Quasi-one-dimensional magnetic interactions and conduction electrons in EuCu5 and EuAu5 with the characteristic hexagonal structure2020

    • Author(s)
      Matsuda S.、Ota J.、Nakaima K.、Iha W.、Gouchi J.、Uwatoko Y.、Nakashima M.、Amako Y.、Honda F.、Aoki D.、Nakamura A.、Takeuchi T.、Haga Y.、Harima H.、Hedo M.、Nakama T.、Onuki Y.
    • Journal Title

      Philosophical Magazine

      Volume: 100 Pages: 1244~1257

    • DOI

      10.1080/14786435.2019.1708498

    • Peer Reviewed
  • [Journal Article] Anisotropic Kondo pseudogap in URu2Si22020

    • Author(s)
      Buhot J.、Montiel X.、Gallais Y.、Cazayous M.、Sacuto A.、Lapertot G.、Aoki D.、Hussey N. E.、Lacroix C.、Pepin C.、Burdin S.、Measson M.-A.
    • Journal Title

      Physical Review B

      Volume: 101 Pages: 245103

    • DOI

      10.1103/PHYSREVB.101.245103

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Destabilization of hidden order in URu2Si2 under magnetic field and pressure2020

    • Author(s)
      Knafo W.、Araki S.、Lapertot G.、Aoki D.、Knebel G.、Braithwaite D.
    • Journal Title

      Nature Physics

      Volume: 16 Pages: 942~948

    • DOI

      10.1038/S41567-020-0927-4

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Magnetic and transport properties of new ternary uranium-based germanide U2Rh3Ge52020

    • Author(s)
      Li D X、Shimizu Y、Nakamura A、Maurya A、Sato Y J、Homma Y、Honda F、Aoki D
    • Journal Title

      Journal of Physics: Condensed Matter

      Volume: 32 Pages: 495804

    • DOI

      10.1088/1361-648X/ABB31A

    • Peer Reviewed
  • [Journal Article] Magnetic structure of Cd-dopedCeIrIn52020

    • Author(s)
      Beauvois K.、Qureshi N.、Tsunoda R.、Hirose Y.、Settai R.、Aoki D.、Rodiere P.、McCollam A.、Sheikin I.
    • Journal Title

      Physical Review B

      Volume: 101 Pages: 195146

    • DOI

      10.1103/PHYSREVB.101.195146

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Evidence of Fermi surface reconstruction at the metamagnetic transition of the strongly correlated superconductor UTe22020

    • Author(s)
      Niu Q.、Knebel G.、Braithwaite D.、Aoki D.、Lapertot G.、Valiska M.、Seyfarth G.、Knafo W.、Helm T.、Brison J.-P.、Flouquet J.、Pourret A.
    • Journal Title

      Physical Review Research

      Volume: 2 Pages: 033179

    • DOI

      10.1103/PHYSREVRESEARCH.2.033179

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Pseudo-Triplet 5f Electron State in the Heavy Fermion Superconductor NpPd5Al22020

    • Author(s)
      Metoki Naoto、Aoki Dai、Griveau Jean-Christophe、Ohtsuki Junya
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 89 Pages: 024707

    • DOI

      10.7566/JPSJ.89.024707

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Field-angular Dependence of Pairing Interaction in URhGe: Comparison with UCoGe2020

    • Author(s)
      Tokunaga Yo、Aoki Dai、Mayaffre Hadrien、Kramer Steffen、Julien Marc-Henri、Berthier Claude、Horvatic Mladen、Sakai Hironori、Kambe Shinsaku、Hattori Taisuke、Araki Shingo
    • Journal Title

      JPS Conference Proceedings

      Volume: 30 Pages: 011037

    • DOI

      10.7566/JPSCP.30.011037

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] The f-electron State of the Heavy Fermion Superconductor NpPd5Al2 and the Isostructural Family2020

    • Author(s)
      N. Metoki, A. A. Aczel, D. Aoki, S. Chi, J. A. Fernandez-Baca, J.-C. Griveau, M. Hagihala, T. Hong, Y. Haga, K. Ikeuchi, Y. Inamura, K. Kamazawa, R. Kajimoto, H. Kitazawa, T. Masuda, M. Matsuda, M. Nakamura, J. Ohtsuki, D. Pajerowski, H. S. Suzuki, E. Yamamoto, H. Yamauchi
    • Journal Title

      JPS Conference Proceedings

      Volume: 30 Pages: 011123

    • DOI

      10.7566/JPSCP.30.011123

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Single Crystal Growth and de Haas-van Alphen Effect of Non-Centrosymmetric Heavy-Fermion Compound UPt52020

    • Author(s)
      Sato Yoshiki J.、Harima Hisatomo、Nakamura Ai、Maurya Arvind、Shimizu Yusei、Homma Yoshiya、Li Dexin、Honda Fuminori、Aoki Dai
    • Journal Title

      JPS Conference Proceedings

      Volume: 30 Pages: 011171

    • DOI

      10.7566/JPSCP.30.011171

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Single Crystal Growth and Anisotropy of the Upper Critical Field of CeIr32020

    • Author(s)
      Sato Yoshiki J.、Shimizu Yusei、Honda Fuminori、Nakamura Ai、Homma Yoshiya、Maurya Arvind、Li Dexin、Aoki Dai
    • Journal Title

      JPS Conference Proceedings

      Volume: 29 Pages: 011007

    • DOI

      10.7566/JPSCP.29.011007

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Spin-Triplet Superconductivity in UTe2 and Ferromagnetic Superconductors2020

    • Author(s)
      Aoki Dai、Nakamura Ai、Honda Fuminori、Li DeXin、Homma Yoshiya、Shimizu Yusei、Sato Yoshiki J.、Knebel Georg、Brison Jean-Pascal、Pourret Alexandre、Braithwaite Daniel、Lapertot Gerard、Niu Qun、Valiska Michal、Harima Hisatomo、Flouquet Jacques
    • Journal Title

      JPS Conference Proceedings

      Volume: 30 Pages: 011065

    • DOI

      10.7566/jpscp.30.011065

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Electrical Transport under Pressure in Non-centrosymmetric URhSn2020

    • Author(s)
      Maurya Arvind、Honda Fuminori、Shimizu Yusei、Nakamura Ai、Sato Yoshiki J.、Homma Yoshiya、Li DeXin、Aoki Dai
    • Journal Title

      JPS Conference Proceedings

      Volume: 29 Pages: 014003

    • DOI

      10.7566/JPSCP.29.014003

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Multiple Superconducting Phases and Unusual Enhancement of the Upper Critical Field in UTe22020

    • Author(s)
      Aoki Dai、Honda Fuminori、Knebel Georg、Braithwaite Daniel、Nakamura Ai、Li DeXin、Homma Yoshiya、Shimizu Yusei、Sato Yoshiki J.、Brison Jean-Pascal、Flouquet Jacques
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 89 Pages: 053705

    • DOI

      10.7566/JPSJ.89.053705

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Anisotropy of the Upper Critical Field in the Heavy-Fermion Superconductor UTe2 under Pressure2020

    • Author(s)
      Knebel Georg、Kimata Motoi、Valiska Michal、Honda Fuminori、Li DeXin、Braithwaite Daniel、Lapertot Gerard、Knafo William、Pourret Alexandre、Sato Yoshiki J.、Shimizu Yusei、Kihara Takumi、Brison Jean-Pascal、Flouquet Jacques、Aoki Dai
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 89 Pages: 053707

    • DOI

      10.7566/JPSJ.89.053707

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Electronic Nematicity in URu2Si2 Revisited2020

    • Author(s)
      Wang Liran、He Mingquan、Hardy Frederic、Aoki Dai、Willa Kristin、Flouquet Jacques、Meingast Christoph
    • Journal Title

      Physical Review Letters

      Volume: 124 Pages: 257601

    • DOI

      10.1103/PhysRevLett.124.257601

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Orientation of point nodes and nonunitary triplet pairing tuned by the easy-axis magnetization in UTe22020

    • Author(s)
      Kittaka Shunichiro、Shimizu Yusei、Sakakibara Toshiro、Nakamura Ai、Li Dexin、Homma Yoshiya、Honda Fuminori、Aoki Dai、Machida Kazushige
    • Journal Title

      Physical Review Research

      Volume: 2 Pages: 032014

    • DOI

      10.1103/PhysRevResearch.2.032014

    • Peer Reviewed
  • [Journal Article] Fermi Surface of the Heavy-fermion Superconductor PrTi2Al202020

    • Author(s)
      Kubo Tomoya、Matsuoka Eiich、Kotegawa Hisashi、Tou Hideki、Nakamura Ai、Aoki Dai、Harima Hisatomo、Sugawara Hitoshi
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 89 Pages: 084704

    • DOI

      10.7566/JPSJ.89.084704

    • Peer Reviewed
  • [Journal Article] de Haas-van Alphen Effect and Fermi Surface Properties in Single-Crystalline ThCu2Si22020

    • Author(s)
      Nakamura Ai、Honda Fuminori、Homma Yoshiya、Li Dexin、Shimizu Yusei、Maurya Arvind、Sato Yoshiki J.、Harima Hisatomo、Onuki Yoshichika、Aoki Dai
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 89 Pages: 094703

    • DOI

      10.7566/JPSJ.89.094703

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Extremely large magnetoresistance, anisotropic Hall effect, and Fermi surface topology in single-crystalline WSi22020

    • Author(s)
      Mondal Rajib、Sasmal Souvik、Kulkarni Ruta、Maurya Arvind、Nakamura Ai、Aoki Dai、Harima Hisatomo、Thamizhavel Arumugam
    • Journal Title

      Physical Review B

      Volume: 102 Pages: 115158

    • DOI

      10.1103/PhysRevB.102.115158

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Orbital crossing in spin-split Fermi surfaces and anisotropic effective mass of the noncentrosymmetric heavy-fermion paramagnet UPt52020

    • Author(s)
      Sato Yoshiki J.、Harima Hisatomo、Nakamura Ai、Maurya Arvind、Shimizu Yusei、Homma Yoshiya、Li Dexin、Honda Fuminori、Aoki Dai
    • Journal Title

      Physical Review B

      Volume: 102 Pages: 125114

    • DOI

      10.1103/PhysRevB.102.125114

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Strong magnetic anisotropy and unusual magnetic field reinforced phase in URhSn with a quasi-kagome structure2020

    • Author(s)
      Shimizu Yusei、Miyake Atsushi、Maurya Arvind、Honda Fuminori、Nakamura Ai、Sato Yoshiki J.、Li Dexin、Homma Yoshiya、Yokoyama Makoto、Tokunaga Yo、Tokunaga Masashi、Aoki Dai
    • Journal Title

      Physical Review B

      Volume: 102 Pages: 134411

    • DOI

      10.1103/PhysRevB.102.134411

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Anisotropy of upper critical field and surface superconducting state in the intermediate-valence superconductor CeIr32020

    • Author(s)
      Sato Yoshiki J.、Honda Fuminori、Shimizu Yusei、Nakamura Ai、Homma Yoshiya、Maurya Arvind、Li Dexin、Koizumi Takatsugu、Aoki Dai
    • Journal Title

      Physical Review B

      Volume: 102 Pages: 174503

    • DOI

      10.1103/PhysRevB.102.174503

    • Peer Reviewed / Int'l Joint Research
  • [Presentation] 新奇スピン三重項超伝導体UTe2の磁場誘起超伝導2021

    • Author(s)
      青木大
    • Organizer
      日本物理学会年次大会
  • [Presentation] Multiple superconducting phases and field-induced phenomena in UTe22021

    • Author(s)
      Dai Aoki
    • Organizer
      APS march meeting 2021
    • Int'l Joint Research / Invited
  • [Presentation] New Uranium-Based Superconductor: UTe22020

    • Author(s)
      Dai Aoki
    • Organizer
      Virtual Theoretical & Experimental Magnetism Meeting (vTEMM) 2020 and UK-Japan Workshop on Strongly Correlated Electron Systems
    • Int'l Joint Research / Invited
  • [Presentation] UTe2のスピン三重項超伝導と磁場誘起現象2020

    • Author(s)
      青木大
    • Organizer
      強磁場セミナー(物性研)
  • [Presentation] Field reentrant superconductivity and multiple phases in UTe22020

    • Author(s)
      Dai Aoki
    • Organizer
      Condensed Matter Physics in All the Cities: Online 2020
    • Int'l Joint Research / Invited
  • [Presentation] UTe2の基礎物性2020

    • Author(s)
      青木大
    • Organizer
      日本物理学会秋季大会(一般シンポジウム)
    • Invited
  • [Presentation] 新奇スピン三重項超伝導体UTe2の磁場誘起超伝導2020

    • Author(s)
      青木大
    • Organizer
      日本物理学会秋季大会(JPSJフレンドシップミーティング)
  • [Presentation] Multiple SC phases for H || a, b, c-axes2020

    • Author(s)
      Dai Aoki
    • Organizer
      UTe2 online workshop
    • Int'l Joint Research
  • [Presentation] Reentrant superconductivity and multiple superconducting phases in UTe22020

    • Author(s)
      Dai Aoki
    • Organizer
      SCES 2020 Plenary Colloquium
    • Int'l Joint Research / Invited
  • [Presentation] Field-reentrant and multiple superconducting phases in novel spin-triplet superconductor UTe22020

    • Author(s)
      Dai Aoki
    • Organizer
      IRN-APERIODIC
    • Int'l Joint Research / Invited
  • [Presentation] Field induced phenomena and multiple superconducting phases in novel spin-triplet superconductor UTe22020

    • Author(s)
      Dai Aoki
    • Organizer
      QMC Colloquium at UMD
    • Int'l Joint Research
  • [Presentation] Fermi surface properties and heavy fermion superconductivity in Np115 systems and related materials2020

    • Author(s)
      Dai Aoki
    • Organizer
      20 years of the 115's: past, present, and future
    • Int'l Joint Research / Invited

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Published: 2022-12-28  

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