Fundamental studies on the practical use of liquid helium-free, medium-temperature superconducting wires

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02681
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 31020:Earth resource engineering, Energy sciences-related
• Research Institution: Nihon University (2022); Nagoya University (2020-2021)
• Principal Investigator: IIDA Kazumasa 日本大学, 生産工学部, 教授 (90749384)
• Co-Investigator(Kenkyū-buntansha): 畑野 敬史 名古屋大学, 工学研究科, 准教授 (00590069) ; 生田 博志 名古屋大学, 工学研究科, 教授 (30231129)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 鉄系超伝導 / トポタクティック反応 / 水素 / 臨界電流

Outline of Final Research Achievements

In this study, we have fabricated epitaxial thin films of the high-Tc iron-based superconductor NdFeAs(O,H), in which the oxygen site is partially replaced by hydrogen, and evaluated the physical properties of NdFeAs(O,H). As a result, NdFeAs(O,H) has higher superconducting properties (e.g. critical current density Jc, irreversibility field and low anisotropy), than NdFeAs(O,F). However, the decay of Jc with external magnetic fields was large, hence it is necessary to improve the in-field Jc. Although the inter-grain Jc has already begun to decay at a grain boundary angle of 6 degree, the absolute value was 6.2 MA/cm2, which is more than one order of magnitude higher than that in iron-based superconductors. Therefore, NdFeAs(O,H) is a suitable material for application among iron-based superconductors.

Free Research Field

物性，薄膜工学

Academic Significance and Societal Importance of the Research Achievements

鉄系超伝導体の中でも最も転移温度の高いLnFeAs(O,H) (Ln: ランタノイド元素）の物性を明らかにすることは，これまで大きな単結晶が作製されなかったため遅れていた．そのような中，NdFeAs(O,H)エピタキシャル薄膜を作製し，物性を明らかにしたことは学術的に意義は大きい．さらに応用研究で重要となる臨界電流特性などの評価を行なったことは工学的にも意義があると言える．