Novel chalcogenide intercalation compounds with simultaneous control of dimensionality and carrier concentration

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14418
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Ichinoseki National College of Technology
• Principal Investigator: Sato Kazuki 一関工業高等専門学校, その他部局等, 助教 (80847286)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 超伝導 / インターカレーション / 層間化合物

Outline of Final Research Achievements

We have succeeded in synthesizing three new FeSe-based intercalation compounds with dramatically extended interlayer lengths by co-intercalation of Li and linear monoamine in the iron-based superconductor FeSe, and found that these samples exhibit a Tc ~43 K. The interlayer length of the sample co-intercalated with Li and octadecylamine is 55.7 Å, which is a significant improvement over the highest value of 19.0 Å reported previously for FeSe-based intercalation compounds. We also succeeded in synthesizing a new FeSe-based superconductor (Tc ~ 43 K) by co-intercalation of alkaline earth metals and ethylenediamine using the solvothermal method, in which the reaction takes place under high temperature and high pressure.
Furthermore, co-intercalation of Li and ethylenediamine into transition metal dichalcogenides 1T'-MoTe2 and Td-WTe2 was successfully achieved and Tc was found to be 5.6 K and 3.8 K, respectively.

Free Research Field

超伝導

Academic Significance and Societal Importance of the Research Achievements

様々な層状カルコゲナイド系物質に金属と有機分子の共挿入を試み，キャリア濃度と層間距離（次元性）を同時に制御することで，多くの新規超伝導体を合成することに成功した。直鎖モノアミンを用いると，層間にモノアミンが縦に2分子配列し，層間距離を大幅に伸長できることが明らかになった。この手法は他の層状物質にも応用可能であり，層間距離制御に関する新たな知見を得ることができた。
さらに，Type-Ⅱワイル半金属候補物質として注目されている遷移金属ダイカルコゲナイドWTe2とMoTe2において初めて共挿入に成功し，超伝導を観測したことは，トポロジカル物質の研究分野においても非常に重要な成果である。