Development of a sub-picometer dilatometer and its application to the research of novel superconducting phases under a precise control of the magnetic-field orientation

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K20893
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 13:Condensed matter physics and related fields
• Research Institution: Chuo University
• Principal Investigator: Kittaka Shunichiro 中央大学, 理工学部, 准教授 (80579805)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: 膨張計 / 磁歪 / FFLO超伝導 / 磁場方位制御

Outline of Final Research Achievements

In this study, we developed a compact homemade dilatometer with a high resolution better than sub-picometer, and performed low-temperature magnetostriction measurements with precise control of the magnetic-field orientation, in order to study novel superconducting phases. We used this dilatometer for the study of unconventional superconductors CeCoIn5 and Sr2RuO4, and detected weak magnetostriction anomaly suggesting the occurrence of a novel superconducting phase in the field region slightly below the upper critical field. In particular, we found from field-angle-resolved measurements that the magnetostriction anomaly in CeCoIn5 depends on the measured direction of the sample length. This technique established a new experimental approach to identify the order parameter of novel superconducting phases.

Free Research Field

Condensed matter physics

Academic Significance and Societal Importance of the Research Achievements

本研究では、試料長の変化をサブピコメートルの高感度で検出できるキャパシタンス式膨張計を開発し、ベクトルマグネットおよび希釈冷凍機と組み合わせることで、0.1 K以下の極低温まで磁場角度分解磁歪測定が可能な実験装置を実現した。本装置を用いて超伝導相内部で発現するFFLO相転移の検出にも成功し、CeCoIn5のFFLO相転移が異方的な試料長変化を伴うことを見出した。以上のように、本研究の実施によりFFLO超伝導の新たな研究アプローチを開拓することができた。本装置の応用可能性は極めて広く、非自明な相転移を示す様々な系の研究に応用していくことで物性物理学の発展に今後も幅広く貢献することが期待できる。