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Experimental study on the dynamics of topological defects in solid Helium

Research Project

Project/Area Number 20K03839
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
Research InstitutionAshikaga University

Principal Investigator

Takahashi Daisuke  足利大学, 工学部, 教授 (80415215)

Project Period (FY) 2020-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2023: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000)
Fiscal Year 2022: ¥260,000 (Direct Cost: ¥200,000、Indirect Cost: ¥60,000)
Fiscal Year 2021: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2020: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
Keywords量子固体 / 転位 / 低温技術
Outline of Research at the Start

固体ヘリウム4の転位運動およびそれに伴う剛性変化のメカニズムは転位論の古典動力学理論(Granato-Luckeの理論)と量子固体特有の原子多体交換の相互作用で説明されてきた。しかし,申請者らの研究から,固体中の転位(トポロジカル欠陥)の動的性質に関しては,清浄固体内であっても未だに十分な理解がなされていないといえる。
本研究では,単結自由な状態にした状態で圧縮応力を系統的に加え,せん断弾性率を測定する。これにより,すべり面以外の方向に対する転位の運動および自由度を議論し,量子固体中の転位運動とそのダイナミクスについて明らかにする研究である。

Outline of Final Research Achievements

Solid helium-4 contains only helium-3 isotopes as impurities, it serves as an ideal solid for investigating the dynamic properties of topological defects within the solid. This study examined the dynamic properties of dislocations, which is a typical topological defect in the solid, that contribute to the temperature dependence of the shear modulus, a classical physical quantity of solid helium-4. By measuring the elastic changes in solid helium-4 confined within a double pendulum that shows sensitive responses to elastic modulus variations, we verified observed changes in elastic modulus that are difficult to explain using existing dislocation theories. These results suggest the presence of novel dynamic properties in dislocation motion.

Academic Significance and Societal Importance of the Research Achievements

トポロジカル欠陥としての転位の動的性質は結晶・非結晶体の多くで相転移を含めマクロな物性変化の核心的駆動体となる可能性が示唆されているが,他の系においては転位以外の要因を適切に取り除くことが困難である。一方,固体ヘリウム4は素性の知れた同位体としての不純物のみを考慮することで,転位の動的性質を議論することが可能となる。本研究で明らかになった固体ヘリウム4の新奇な転位ダイナミクス存在の可能性は既存の転位論の深化へ大きく寄与すると考えられる。

Report

(5 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Research-status Report
  • 2021 Research-status Report
  • 2020 Research-status Report
  • Research Products

    (2 results)

All 2023 2020

All Journal Article (2 results) (of which Peer Reviewed: 2 results,  Open Access: 1 results)

  • [Journal Article] Positive Ion Critical Velocity for Nucleation of Quantized Vortices in Isotopically Pure 4He2023

    • Author(s)
      Daisuke Takahashi, Hiroki Ikegami, Kimitoshi Kono
    • Journal Title

      Journal of Low Temperature Physics

      Volume: - Issue: 5-6 Pages: 214-231

    • DOI

      10.1007/s10909-023-02970-6

    • Related Report
      2022 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Study of Rotation Effect in Solid 4He by an Elasticity-Sensitive Torsional Oscillator2020

    • Author(s)
      Tsuiki Tomoya、Takahashi Daisuke、Murakawa Satoshi、Okuda Yuichi、Kono Kimitoshi、Shirahama Keiya
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 89 Issue: 9 Pages: 094601-094601

    • DOI

      10.7566/jpsj.89.094601

    • NAID

      40022344818

    • Related Report
      2020 Research-status Report
    • Peer Reviewed

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Published: 2020-04-28   Modified: 2025-01-30  

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