Developments of reconfigurable quantum superconducting devices based on rotational spin current

• Project/Area Number: 21H05021
• Research Category: Grant-in-Aid for Scientific Research (S)
• Allocation Type: Single-year Grants
• Review Section: Broad Section D
• Research Institution: Kyushu University
• Principal Investigator: 木村 崇 九州大学, 理学研究院, 教授 (80360535)
• Co-Investigator(Kenkyū-buntansha): 大西 紘平 近畿大学, 理工学部, 准教授 (30722293) ; 野村 清英 九州大学, 理学研究院, 准教授 (70222205)
• Project Period (FY): 2021-07-05 – 2026-03-31
• Project Status: Granted (Fiscal Year 2024)
• Budget Amount: ¥178,620,000 (Direct Cost: ¥137,400,000、Indirect Cost: ¥41,220,000); Fiscal Year 2025: ¥20,800,000 (Direct Cost: ¥16,000,000、Indirect Cost: ¥4,800,000); Fiscal Year 2024: ¥23,660,000 (Direct Cost: ¥18,200,000、Indirect Cost: ¥5,460,000); Fiscal Year 2023: ¥20,410,000 (Direct Cost: ¥15,700,000、Indirect Cost: ¥4,710,000); Fiscal Year 2022: ¥30,940,000 (Direct Cost: ¥23,800,000、Indirect Cost: ¥7,140,000); Fiscal Year 2021: ¥82,810,000 (Direct Cost: ¥63,700,000、Indirect Cost: ¥19,110,000)
• Keywords: トリプレットクーパー対 / スピン注入 / 準粒子 / 超伝導 / スピン流 / スピントリプレット / 回転スピン流 / スピンホール効果 / トリプレット超伝導

Outline of Research at the Start

本研究では、他に類を見ない特性を有する超伝導デバイスに、スピン自由度を絡め、更なる機能性を付加した応用の実現を目指す。申請者が確立している回転スピン流の生成技術、およびスピン偏極準粒子とクーパー対の共存状態の創出技術を用いて、スピン三重項クーパー対やパイ接合ジョセフソン回路などの機能性が高い量子状態を実現する。更に、それらとコヒーレンス制御技術へと高度化することで、再構成が可能で革新的な高機能量子デバイスの実現を目指す。

Outline of Annual Research Achievements

本研究では、申請者が開発した強磁性体/常磁性常伝導体/超伝導体からなる三層構造、及び回転スピン流注入技術を用いて、超伝導体中にスピン三重項クーパ対を形成し、更に、得られたスピン・トリプレット状態を活用して、超高速な動作をする革新的スピンデバイス、及び新奇なスピン量子ビットの実現を目指す。研究体制として、代表者が純スピン流デバイスの素子性能の向上と超伝導スピンデバイス構造の提案・試作、分担者が、超伝導デバイスの素子作製、及び測定、また、分担者が、トリプレットクーパー対や新奇構造の妥当性などの理論的サポートを行う。更に、博士研究員を雇用し、実験研究を加速させ、着実な成果創出を目指す。
今年度は、ようやく稼働した冷凍機を用いて、Al 超伝導素子へのスピン注入を行った。実験結果から、スピン偏極準粒子が非偏極準粒子に比べ、長い準粒子緩和長を持つことが明瞭に示され、Nb よりもスピン注入効果が有効になること、また、Al のスピン軌道相互作用が小さいことが確認された。
スピン注入効率の増大に関しては、斜め蒸着法を用いたナノピラー構造の作製技術を開発し、効率の増大に成功した。さらには、新しい超伝導物質への取り組みや準粒子緩和長の高精度評価などにも成功している。また、新たなスピン注入源の可能性として、二次元物質を用いた手法やスピンホール効果などを組み込んだ新型素子の提案と実証を行った。特に、二次元物質に関しては、高い垂直磁気異方性とスピンホール角、異常ネルンスト角を有していることが判明し、今後の研究展開に大きな可能性を有することが期待される。

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

冷凍機がようやく稼働を始め、He3 温度における安定的な実験が可能になり、Al 超伝導スピン注入素子の測定が系統的に実施できるようになった。スピン偏極準粒子の緩和長の評価も可能となり、着実な成果が得ることができた。

Strategy for Future Research Activity

スピン偏極準粒子注入技術は確立できたが、トリプレットクーパー対形成に向け、スピン注入効率の更なる向上や、発熱効果の更なる低減が必要である。そのため、スピン注入源電極の更なる物質・構造最適化を行い、多端子スピン注入を用いた回転スピン流を形成し、シングレットトリプレット変換の実現を目指す。

Assessment Rating

Interim Assessment Comments (Rating)

A-: In light of the aim of introducing the research area into the research categories, the expected progress in research has been made on the whole though a part of it has been delayed.

Research Products

• [Journal Article] Efficient Thermo‐Spin Conversion in van der Waals Ferromagnet FeGaTe (2023)
  • Author(s): Liu Shuhan、Hu Shaojie、Cui Xiaomin、Kimura Takashi
  • Journal Title: Advanced Materials Volume: 36 Issue: 14
  • DOI: 10.1002/adma.202309776
  • Peer Reviewed
• [Journal Article] Field and temperature-controlled positive and negative exchange biases in CoO/YIG bilayers on GGG(111) (2023)
  • Author(s): Chang Po-Chun、Liu Shi-Yu、Lin Hung-Lin、Hu Shaojie、Kimura Takashi、Lo Fang-Yuh、Lin Wen-Chin
  • Journal Title: Journal of Alloys and Compounds Volume: 968 Pages: 172081-172081
  • DOI: 10.1016/j.jallcom.2023.172081
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Efficient Electrical Manipulation of the Magnetization Process in an Epitaxially Controlled Co2FeSi/BaTiO Multiferroic Interface (2023)
  • Author(s): Hu Shaojie、Yamada Shinya、Chang Po-Chun、Lin Wen-Chin、Hamaya Kohei、Kimura Takashi
  • Journal Title: Physical Review Applied Volume: 20 Issue: 3 Pages: 034029-034029
  • DOI: 10.1103/physrevapplied.20.034029
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Experimental and Theoretical Evaluation for Pressure Effects on Spin Hall Effect in Pt (2023)
  • Author(s): Iimori Riku、Obinata Sora、Yamazaki Taishiro、Mitsuda Akihiro、Kimura Takashi
  • Journal Title: IEEE Transactions on Magnetics Volume: 59 Issue: 11 Pages: 1-5
  • DOI: 10.1109/tmag.2023.3283467
  • Peer Reviewed
• [Journal Article] Magneto-Electric Voltage Due to Microwave Heating in CoFeB/Heavy Metal Bilayer System (2023)
  • Author(s): Obinata S.、Iimori R.、Tanaka T.、Kajima R.、Kimura T.
  • Journal Title: IEEE Transactions on Magnetics Volume: 59 Issue: 11 Pages: 1-4
  • DOI: 10.1109/tmag.2023.3283499
  • Peer Reviewed
• [Journal Article] Enhanced spin accumulation in nano-pillar-based lateral spin valve using spin reservoir effect (2022)
  • Author(s): Cui Xiaomin、Hu Shaojie、Kimura Takashi
  • Journal Title: Journal of Physics D: Applied Physics Volume: 55 Issue: 16 Pages: 165004-165004
  • DOI: 10.1088/1361-6463/ac47bf
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Experimental Evaluation of 3D Heat Flow Using Magneto‐Thermoelectric Effects in a Ferromagnetic Nanowire (2022)
  • Author(s): Kamruzzaman Md、Hu Shaojie、Ohnishi Kohei、Kimura Takashi
  • Journal Title: physica status solidi (RRL) ? Rapid Research Letters Volume: - Issue: 5 Pages: 2100608-2100608
  • DOI: 10.1002/pssr.202100608
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Influence of heat flow control on dynamical spin injection in CoFeB/Pt/CoFeB trilayer (2022)
  • Author(s): Obinata Sora、Iimori Riku、Ohnishi Kohei、Kimura Takashi
  • Journal Title: Scientific Reports Volume: 12 Issue: 1 Pages: 3467-3470
  • DOI: 10.1038/s41598-022-06784-6
  • Peer Reviewed / Open Access
• [Journal Article] Pressure-induced enhancement of spin-charge conversion efficiency in CoFeB/Pt bilayer (2022)
  • Author(s): Iimori Riku、Obinata Sora、Mitsuda Akihiro、Kimura Takashi
  • Journal Title: Applied Physics Express Volume: 15 Issue: 3 Pages: 033003-033003
  • DOI: 10.35848/1882-0786/ac5501
  • Peer Reviewed
• [Journal Article] Quantitative Evaluation of Heating Effect on Dynamical Spin Injection Using CoFeB/Pt/CoFeB Trilayered Film (2022)
  • Author(s): Obinata S.、Iimori R.、Ohnishi K.、Kimura T.
  • Journal Title: IEEE Transactions on Magnetics Volume: 58 Issue: 2 Pages: 1-4
  • DOI: 10.1109/tmag.2021.3087797
  • Peer Reviewed
• [Journal Article] Relaxation Process of Spin-Polarized Quasiparticles in a Superconducting Nb Wire (2022)
  • Author(s): Iwahori T.、Mizokami K.、Matsuda R.、Ohnishi K.、Kimura T.
  • Journal Title: IEEE Transactions on Magnetics Volume: 58 Issue: 2 Pages: 1-4
  • DOI: 10.1109/tmag.2021.3083059
  • Peer Reviewed
• [Journal Article] The positive exchange bias property with hopping switching behavior in van der Waals magnet FeGeTe (2022)
  • Author(s): Hu Shaojie、Cui Xiaomin、Yue Zengji、Wang Pangpang、Guo Lei、Ohnishi Kohei、Wang Xiaolin、Kimura Takashi
  • Journal Title: 2D Materials Volume: 9 Issue: 1 Pages: 015037-015037
  • DOI: 10.1088/2053-1583/ac456f
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Effective modulation of spin accumulation using a ferromagnetic/nonmagnetic bilayer spin channel (2021)
  • Author(s): Ariki Taisei、Nomura Tatsuya、Ohnishi Kohei、Kimura Takashi
  • Journal Title: Journal of Physics D: Applied Physics Volume: 55 Issue: 9 Pages: 095302-095302
  • DOI: 10.1088/1361-6463/ac34aa
  • Peer Reviewed
• [Journal Article] Nonlinear power dependence of ferromagnetic resonance in NiFe/Pt/CoFeB trilayer (2021)
  • Author(s): Yafuso Minoru、Miyazaki Keishi、Takayama Yusei、Obinata Sora、Kimura Takashi
  • Journal Title: Journal of Physics: Condensed Matter Volume: 34 Issue: 4 Pages: 045801-045801
  • DOI: 10.1088/1361-648x/ac26f8
  • Peer Reviewed
• [Presentation] Spin transport and spin thermo-electric properties of 2D vdW FeGaTe film (2024)
  • Author(s): Takashi Kimura
  • Organizer: Frontier Material Science
  • Int'l Joint Research / Invited
• [Presentation] Heat transports & magneto-thermoelectric effects in nano spintronic devices (2024)
  • Author(s): Takashi Kimura
  • Organizer: AVS Science & Technology of Materials, Interfaces, and Processing
  • Int'l Joint Research / Invited
• [Presentation] Heat transports & magneto-thermoelectric effects in nano spintronic devices (2023)
  • Author(s): Takashi Kimura
  • Organizer: Coumpond Semiconductor Week
  • Int'l Joint Research / Invited
• [Presentation] 超伝導/常伝導体界面によるスピン流制御 (2023)
  • Author(s): 大西紘平
  • Organizer: 第70回 応用物理学会 春季学術講演会
  • Invited
• [Presentation] スピン依存型電気伝導および熱伝導の実験的探索 (2022)
  • Author(s): 木村 崇
  • Organizer: 名古屋大学物理学教室談話会
• [Presentation] Study of nano-scale heat transports using magneto-thermoelectric effects (2022)
  • Author(s): Takashi Kimura
  • Organizer: 6th International Symposium on Frontiers in Materials Science
  • Int'l Joint Research / Invited
• [Presentation] Spin Absorption Effects due to Various Functional Materials (2022)
  • Author(s): Takashi Kimura
  • Organizer: Annual Meeting of the Physical Society of Taiwan
  • Int'l Joint Research / Invited
• [Presentation] Non-local spin transport in superconductor / ferromagnet hybrid lateral structures (2021)
  • Author(s): Kohei Ohnishi
  • Organizer: International Conference on Superconductivity and Magnetism
  • Int'l Joint Research / Invited