Realization of bulk-superconductivity in new nickelate thin film superconductor

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04638
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26020:Inorganic materials and properties-related
• Research Institution: Yokohama National University
• Principal Investigator: Uehara Masatomo 横浜国立大学, 大学院工学研究院, 准教授 (60323929)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: Ni酸化物 / 高温超伝導 / ドーピング / 層状化合物

Outline of Final Research Achievements

The goal of the project is the realization of bulk-superconductivity in ①Pr4Ni3O8 and ②(Ln,A)NiO2 (Ln=lanthanide, A=Sr,Ca). ①By substituting of Ni(1) site by 3d-elements, carrier number was optimized to induce superconductivity. XAFS and Seebeck measurements showed the controversial results on the carrier concentration. An electrical structure model which can explain the discrepant result was proposed. Neutron diffraction measurement revealed that the dopant element mainly entered into Ni(1) site but a few % of dopant entered in Ni(2). ②Removal of excess oxygen that may be an obstacle to superconductivity became easier when Ln-size became smaller. But the semiconducting character became stronger.
Though the superconductivity didn’t show up in both system, many of knowledge on electrical and structural properties was obtained.

Free Research Field

固体物理

Academic Significance and Societal Importance of the Research Achievements

新超伝導体(Nd,Sr)NiO2は銅酸化物高温超伝導体と似てるが故に物性の詳細な比較が可能であり、高温超伝導機構解明や、約30年間、130 Kで頭打ちである超伝導転移温度を上昇させる指針抽出に大きく寄与するであろう事から非常に注目されている。しかし薄膜でしか超伝導が発現しないため研究の展開は限定的であり、バルク体での超伝導実現が熱望されている。これを受け①Pr4Ni3O8、②(Ln,A)NiO2(Ln=ランタノイド、A=Sr,Ca)バルク体での超伝導発現を目指した。両系において超伝導実現に至らなかったが、超伝導発現に向け、解決すべき点が明確になり、また両系の物性についての多くの知見が得られた。