Exploration and control of metastable superconductivity with ultra rapid-cooling methods

• Project/Area Number: 18H01168
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: The University of Tokyo
• Principal Investigator: Fumitaka Kagawa 東京大学, 大学院工学系研究科(工学部), 准教授 (30598983)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥18,070,000 (Direct Cost: ¥13,900,000、Indirect Cost: ¥4,170,000); Fiscal Year 2020: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000); Fiscal Year 2019: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000); Fiscal Year 2018: ¥14,430,000 (Direct Cost: ¥11,100,000、Indirect Cost: ¥3,330,000)
• Keywords: 超伝導 / 不揮発相制御 / 急冷 / 遷移金属ダイカルコゲナイド / 準安定 / 強相関電子系

Outline of Final Research Achievements

We have succeeded in reversible and nonvolatile conversion of zero-resistance and finite-resistance states in the transition metal dichalcogenide IrTe2 by alternatingly applying electrical pulses of different intensities and pulse widths. This is the first time in more than 100 years of superconductivity research that such a control of superconductivity by applying electric pulses has been achieved. We also succeeded in visualizing the spatial coexistence of superconducting and normal-conducting phases on a few um scale using a scanning Raman microscopy. The observed domain structure has domain walls along specific crystal axes, indicating the strong influence of a strain field on the domain formation.

Academic Significance and Societal Importance of the Research Achievements

本研究の目的は準安定超伝導の実現・制御を可能にする新しい手法を提示・実証することにあった。具体的には、圧力・元素置換・電界効果といった従来の手法を一切用いず、代わりに急冷という平衡熱力学の枠組みを逸脱した手法を用いることで、熱力学的には本来非超伝導体である物質に超伝導を実現させる。ただし、準安定相として、である。当初の目標が達成できたことで、超伝導制御に関して新しい手法を提示することができた。これにより、書き換え可能な超伝導回路といった機能性実現への道が拓かれたと考えている。

Research Products

• [Journal Article] Kinetic approach to superconductivity hidden behind a competing order (2018)
  • Author(s): Oike Hiroshi、Kamitani Manabu、Tokura Yoshinori、Kagawa Fumitaka
  • Journal Title: Science Advances Volume: 4 Issue: 10
  • DOI: 10.1126/sciadv.aau3489
  • Peer Reviewed / Open Access
• [Presentation] Pulse-driven nonvolatile phase change of electronic/magnetic/superconducting states (2021)
  • Author(s): Fumitaka Kagawa
  • Organizer: 日本化学会
  • Int'l Joint Research / Invited
• [Presentation] Narrow-band resistance noise and mode-locking phenomena of a skyrmion lattice in a microfabricated MnSi (2021)
  • Author(s): Fumitaka Kagawa
  • Organizer: SKYMAG2021
  • Int'l Joint Research / Invited
• [Presentation] IrTe2微小結晶における確率的相転移ダイナミクスの実空間観測 (2021)
  • Author(s): 武田和大, 大池広志, 上谷学, 十倉好紀, 賀川史敬
  • Organizer: 日本物理学会
• [Presentation] フェーズフィールド法を用いた1次相転移ダイナミクスの体積・冷却速度依存性の研究 (2021)
  • Author(s): 西澤葉, 大池広志, 賀川史敬
  • Organizer: 日本物理学会
• [Presentation] Kinetic approach to superconductivity hidden behind a competing order (2019)
  • Author(s): F. Kagawa
  • Organizer: International Workshop on Strange Metals and Bad Metals
  • Int'l Joint Research / Invited
• [Presentation] Charge glass transition in a geometrically frustrated strongly correlated electron system (2019)
  • Author(s): F. Kagawa
  • Organizer: 2019 International Workshop on Glass Physics in Beijing
  • Int'l Joint Research / Invited
• [Presentation] A hidden role of the smallness of the material in flexible devices (2019)
  • Author(s): F. Kagawa
  • Organizer: Materials Research Meeting 2019
  • Int'l Joint Research / Invited
• [Presentation] Two kinetic approaches to metastable electronic states: rapid cooling and sample miniaturization (2018)
  • Author(s): F. Kagawa
  • Organizer: The 43rd International Conference on Coordination Chemistry (ICCC2018)
  • Int'l Joint Research / Invited
• [Presentation] 急冷非平衡状態を利用した準安定相創出と制御 ―磁気スキルミオンや超伝導を例に (2018)
  • Author(s): 賀川 史敬
  • Organizer: 第１０回トポロジー連携研究会「非平衡系・非エルミート系の新奇量子現象」
  • Invited
• [Book] 「有機・無機材料の相転移ダイナミクス」中、第11章「強相関電子物質の相転移ダイナミクスと準安定相制御」 (2020)
  • Author(s): 賀川史敬, 十倉好紀
  • Publisher: 化学同人
  • ISBN: 9784759813951
• [Book] 有機・無機材料の相転移ダイナミクス（第１１章を執筆） (2020)
  • Author(s): 賀川史敬、十倉好紀
  • Total Pages: 196
  • Publisher: 化学同人
• [Remarks]
  • URL: https://www.riken.jp/press/2018/20181006_1/index.html