Synthesis of single crystals of cuprate superconductors with apical fluorine and study of CDW phase on CuO2 planes without apical oxygen

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K03722
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Tokyo University of Science
• Principal Investigator: Tokiwa Kazuyasu 東京理科大学, 先進工学部電子システム工学科, 教授 (60307709)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 多層型銅酸化物超伝導体 / 単結晶 / Hall効果

Outline of Final Research Achievements

Single crystal samples of Ba2Can-1CunO2n(O, F)2 (n=3~6), which is expected to have ideal CuO2 planes with less disorder, were synthesized and their physical properties were evaluated under a high magnetic field. By growing single-crystal samples under a pressure of 4.5 GPa, we obtained single-crystal samples of n=4~6 with a size of about 1 mm. We measured the Hall effect for the n=4 and n=5 samples under high magnetic fields up to 60 T. The superconductivity could be suppressed for both samples at temperatures of 4 K and magnetic fields above 30 T, but no sign change of the Hall coefficient due to the reconstruction of the Fermi surface was observed.

Free Research Field

超伝導材料

Academic Significance and Societal Importance of the Research Achievements

銅酸化物超伝導体は，発見以来35年以上が経過しているが，いまだに常圧下では最も高い超伝導転移温度を示す。しかし，なぜ高い温度で超伝導が発現するのか最終的な結論には至っていない。頂点フッ素系多層型超伝導体は，クリーンな超伝導の舞台となるCuO2面を持っている。本研究課題では，単位格子中のCuO2面の枚数が異なる単結晶試料を作製することに成功した。これらの単結晶を用いて物性測定を進めることにより，これまで困難であった乱れの少ないCuO2面で発現する物性を明らかにし，超伝導発現機構解明に貢献できるものと考えられる。