Nuclear Magnetic Resonance study of the charge density wave order in the Cu oxide superconductor

• Project/Area Number: 19K03747
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Okayama University
• Principal Investigator: Kawasaki Shinji 岡山大学, 自然科学学域, 准教授 (80397645)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2021: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
• Keywords: 銅酸化物高温超伝導 / 核磁気共鳴 / 電荷密度波 / 銅酸化物高温超伝導体 / 電荷揺らぎ / 高温超伝導 / 銅酸化物 / 擬ギャップ / 一軸歪

Outline of Research at the Start

「超伝導」は、無損失送電や余剰電力蓄電を実現する革新的技術の一つである。本研究は、室温超伝導の最有力候補、銅酸化物高温超伝導体に注目する。銅酸化物は、母物質の反強磁性絶縁体に電子やホールを導入することで「反強磁性が抑制されて超伝導が発現する」ことが知られ、これまでは「磁性」に基づく超伝導機構研究が中心であった。ところが最近、超伝導直前に、電荷が空間的濃淡を作る、電荷密度波（CDW）秩序が発見され、「電荷」が重要であることがわかった。本研究は、磁性にも電荷にも敏感な核磁気共鳴（NMR）法（医療用MRIと原理は同じ）を用いて、新奇なCDWと超伝導との関係を明らかにするため実験的研究を実施する。

Outline of Final Research Achievements

We have conducted nuclear magnetic resonance (NMR) experiments to elucidate the origin of the novel charge density wave order in Cu-oxide (cuprate) superconductor, which is the most promising candidate for room-temperature superconductivity among known superconductors. From systematic measurements, we have obtained new findings that indicate the importance of "charge fluctuation" in addition to spin fluctuation, which has been believed to be the origin of high-temperature superconductivity. Based on our results, further developments of physics of the cuprate superconductivity in theoretical and experimental studies focusing on charge fluctuations are expected. Another purpose of the study was to introduce uniaxial strain, a new external parameter that has recently been the focus of much attention in condensed matter physics, into NMR experiments, and we succeeded in developing an laboratory-made piezoelectric uniaxial strain cell during the research period.

Academic Significance and Societal Importance of the Research Achievements

「超伝導」は将来の脱炭素社会実現に向け有効な省エネ技術の一つであるが、室温超伝導物質がなく、超伝導利用には低温寒剤など超伝導維持コストが普及を妨げている。銅酸化物高温超伝導体は室温超伝導最有力候補物質であるが、超伝導発現機構は不明で室温超伝導開発指針もない。本研究は、銅酸化物の未解明電子状態「擬ギャップ」の起源解明の鍵とされる電荷密度波秩序の研究を実施した。結果、銅酸化物の物理において重要と信じられてきた磁気揺らぎに加え「電荷」揺らぎが重要である証拠を得た。今後高温超伝導発現機構を考える上で電荷に着目した理論や実験研究の発展が期待出来る。さらには将来の脱炭素社会実現に寄与できる。

Research Products

• [Journal Article] Transport signatures of the pseudogap critical point in the cuprate superconductor Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+\delta}$ (2021)
  • Author(s): M. Lizaire, A. Legros, A. Gourgout, S. Benhabib, S. Badoux, F. Laliberte, M.-E. Boulanger, A. Ataei, G. Grissonnanche, D. LeBoeuf, S. Licciardello, S. Wiedmann, S. Ono, H. Raffy, S. Kawasaki, G.-Q. Zheng, N. Doiron-Leyraud, C. Proust, and L. Taillefer
  • Journal Title: Physical Review B Volume: 104 Issue: 1
  • DOI: 10.1103/physrevb.104.014515
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Charge Order and Fluctuations in Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+\delta}$ Revealed by $^{63,65}$Cu-Nuclear Magnetic Resonance (2021)
  • Author(s): Shinji Kawasaki, Madoka Ito, Dai Kamijima, Chengtian Lin, and Guo-qing Zheng
  • Journal Title: J. Phys. Soc. Jpn Volume: 90 Issue: 11 Pages: 111008-111008
  • DOI: 10.7566/jpsj.90.111008
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Antiferromagnetic spin fluctuations and superconductivity in NbRh$_2$B$_2$ and TaRh$_2$B$_2$ with a chiral crystal structure (2021)
  • Author(s): Kazuaki Matano, Ryo Ogura, Mateo Fountaine, Harald O. Jeschke, Shinji Kawasaki, and Guo-qing Zheng
  • Journal Title: Physical Review B Volume: 104 Issue: 22
  • DOI: 10.1103/physrevb.104.224508
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Localized-to-itinerant transition preceding antiferromagnetic quantum critical point and gapless superconductivity in CeRh0.5Ir0.5In5 (2020)
  • Author(s): Kawasaki Shinji、Oka Toshihide、Sorime Akira、Kogame Yuji、Uemoto Kazuhiro、Matano Kazuaki、Guo Jing、Cai Shu、Sun Liling、Sarrao John L.、Thompson Joe D.、Zheng Guo-qing
  • Journal Title: Communications Physics Volume: 3 Issue: 1 Pages: 1-10
  • DOI: 10.1038/s42005-020-00418-x
  • NAID: 120006884910
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] トポロジカル超伝導体Cu$_x$Bi$_2$Se$_3$の作製と物性測定IV (2022)
  • Author(s): 西垣颯, 峰明日香, 横山武蔵, 俣野和明, 神戸高志, 川崎慎司, 鄭国慶
  • Organizer: 日本物理学会第77回年次大会
• [Presentation] 空間反転対称性の破れた超伝導体(Nb,Ta)Rh$_2$B$_2$の超伝導とスピン揺らぎ (2022)
  • Author(s): 俣野和明, 小椋亮, Mateo Fountaine, Harald O. Jeschke, 川崎慎司, 鄭国慶
  • Organizer: 日本物理学会第77回年次大会
• [Presentation] Bi$_2$Sr$_{2-x}$La$_x$CuO$_6$超伝導体における電荷密度波秩序と揺らぎの一軸歪み効果 (2022)
  • Author(s): 佃菜桜, 伊藤まどか, 川崎慎司, Chengtian Lin, 鄭国慶
  • Organizer: 日本物理学会第77回年次大会
• [Presentation] Localized-to-itinerant transition preceding antiferromagnetic quantum critical point and gapless superconductivity in CeRh$_{0.5}$Ir$_{0.5}$In$_5$ (2021)
  • Author(s): S. Kawasaki, T. Oka, A. Sorime, Y. Kogame, K. Uemoto, K. Matano, J. Guo, S. Cai, L. L. Sun, J. L. Sarrao, J. D. Thompson, and Guo-qing Zheng
  • Organizer: International conference on strongly correlated electron systems 2020 (SCES2020)
  • Int'l Joint Research
• [Presentation] 重い電子系反強磁性超伝導体CeRh0.5Ir0.5In5における局在・遍歴転移とギャップレス超伝導 (2021)
  • Author(s): 川崎慎司，岡利英，反り目章，小亀雄司，上本和宏，俣野和明，J. Guo，S. Cai，Liling Sun，J. L. Sarrao，J. D. Thompson，鄭国慶
  • Organizer: 日本物理学会第76回年次大会
• [Presentation] 銅酸化物高温超伝導体Bi2Sr2-xLaxCuO6の一軸圧力下63Cu-NMRによる研究 (2021)
  • Author(s): 吉田翔伍, 川崎慎司, Chengtian Lin, 鄭国慶
  • Organizer: 日本物理学会第76回年次大会
• [Presentation] Charge-density-wave order in single-layered Bi2Sr2-xLaxCuO6 superconductor (2019)
  • Author(s): S. Kawasaki, D. Kamijima, M. Kitahashi, Z. Li, C. T. Lin, P. L. Kuhns, A. P. Reyes, and Guo-qing Zheng
  • Organizer: Spectroscopies in Novel Superconductors (SNS2019)
  • Int'l Joint Research / Invited
• [Presentation] Unconventional Gapless Superconductivity at the Quantum Critical Point in CeRh0.5Ir0.5In5 (2019)
  • Author(s): S. Kawasaki, T. Oka, A. Sorime, Y. Kogame, K. Uemoto, K. Matano, J. Guo, S. Cai, L. L. Sun, J. L. Sarrao, J. D. Thompson, and Guo-qing Zheng
  • Organizer: International conference on strongly correlated electron systems 2019 (SCES2019)
  • Int'l Joint Research
• [Presentation] 重い電子系反強磁性体Ce3Pt4In13の低温高圧下115In-NQR法による研究 (2019)
  • Author(s): 小亀雄司, 伊藤大河, 足立智樹, J. Yang, 川崎慎司, 鄭国慶
  • Organizer: 日本物理学会2019年秋季大会