Study of the electronic states of organic conductors with anisotropic triangular lattice

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03856
• 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 Institute of Technology
• Principal Investigator: Kawamoto Tadashi 東京工業大学, 物質理工学院, 助教 (60323789)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 有機伝導体 / モット絶縁体 / 構造相転移

Outline of Final Research Achievements

A genuine Mott insulator beta-(BEDT-TTF)TaF6 has a 1:1 donor-to-anion ratio without dimerization, and shows an antiferromagnetic state below the Neel temperature of 10 K. By contrast, zeta-(BEDT-TTF)PF6 shows a spin-Peierls state at approximately 40 K. The energy band structure calculated shows a one-dimensional electronic state for zeta-PF6. The square lattice structure of beta-TaF6 is the origin of the antiferromagnetic state. kappa-(BEDT-TTF)2TaF6 with anisotropic triangular lattice shows a paramagnetic state even at 1.6 K. The structural phase transition has been observed at 220 K. The low temperature structure is a domain structure with the triclinic lattice. The crystallographically independent BEDT-TTF is two, A and B molecules, in the low temperature phase.

Free Research Field

有機伝導体の物性

Academic Significance and Societal Importance of the Research Achievements

モット絶縁体は固体物理分野において重要な研究対象であり続けている。本研究において得られた、「真性モット絶縁体」の実験結果や計算結果は有機超伝導の分野だけではなく、広く超伝導や強相関電子系の研究分野において重要であると考えられる。また、異方性の強い三角格子をもつダイマーモット絶縁体の構造相転移の発見は、低温のスピン状態との関連性の解明が期待される。