Elucidation of two-dimensional NbO2 superconducting layer realized by epitaxial thin film

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K15169
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Soma Takuto 東京工業大学, 物質理工学院, 助教 (50868271)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 超伝導 / 強相関電子系 / 二次元物質 / 電気化学 / リチウムイオン電池 / エピタキシャル薄膜 / 量子臨界現象 / フラストレーション

Outline of Final Research Achievements

This study is to elucidate whether the two-dimensional NbO2 superconducting layers in the superconductor Li1-xNbO2 provides new properties and physics.
By measuring physical properties and performing thin-film electrochemical reactions using epitaxial thin films, we proved that "ideal strongly correlated NbO2 superconducting layers are realized in this material" and succeeded in "elucidating the whole picture of the electronic phase exhibited in the NbO2 superconducting layers".
As a result, the two-dimensional NbO2 superconducting layers in this compounds has a strongly correlated single-band structure similar to that of copper oxides, which can be a new stage of "strongly correlated superconductivity" in which the frustrated magnetism and its fluctuations in the layers are related to Cooper pair formation.

Free Research Field

固体化学

Academic Significance and Societal Importance of the Research Achievements

銅酸化物高温超伝導体（1987年ノーベル物理学賞）の発見は基礎・応用両面から大きな発展をもたらし，同様な二次元超伝導層を持つ物質の研究が精力的に行われた。それらは様々な新しい研究領域を開拓し，物性研究の相当な部分を占めるまでとなった。
本研究成果は，Li1-xNbO2が持つ二次元NbO2層がそれらと類似した"強相関超伝導"を発現することを明らかにし，新しい強相関物性の発現やそのメカニズムを解明する新たな舞台となりうることを提示した。