Detection of parity-mixed Cooper pairs in atomic layer superconductors without inversion symmetry

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01817
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: National Institute for Materials Science
• Principal Investigator: YOSHIZAWA Shunsuke 国立研究開発法人物質・材料研究機構, マテリアル基盤研究センター, 主任研究員 (60583276)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 走査型トンネル顕微鏡 / 超伝導 / 電荷密度波 / 遷移金属ダイカルコゲナイド / 原子層物質

Outline of Final Research Achievements

Atomic layer materials grown on substrates are characterized by the breaking of spatial inversion symmetry, and the superconductivity occurring in such materials exhibits a phenomenon called parity mixing. Our goal was to verify this phenomenon using a cryogenic scanning tunneling microscope (STM). During the research period, we improved the quality of atomic layer superconductors formed on silicon substrates, established a vacuum system for growing single layer transition metal dichalcogenides, and developed techniques for measurement and analysis by performing STM experiments on related materials. We discovered that the charge density wave (a superstructure in the charge density) of the transition metal dichalcogenide NbSe2 forms a characteristic domain structure, which was found to be consistent with theoretical work reported some 40 years ago.

Free Research Field

低温物性

Academic Significance and Societal Importance of the Research Achievements

原子層物質をはじめとする高結晶性の2次元超伝導体が研究されるようになり、空間反転対称性の破れに起因する特異な性質に注目が集まっている。これまでの知見は輸送測定によるものが多かったが、本研究計画によりそれらの物性を微視的に明らかにしていく準備が整ったと言える。上述のNbSe2に関する成果は、電荷密度波のような長周期構造を精密解析する有効な手段を提供したほか、NbSe2や関連物質における超伝導と電荷密度波の関係を理解する手がかりとなるので、学術的な重要性が高いと考えている。