Emergence of charge degrees of freedom under high pressure in the organic dimer-Mott insulator β′-(BEDT - TTF) 2 ICl 2

K. Hashimoto*, R. Kobayashi, H. Okamura, H. Taniguchi, Y. Ikemoto, T. Moriwaki, S. Iguchi, M. Naka, S. Ishihara, T. Sasaki

*この研究の対応する著者

研究成果: Article査読

17 被引用数 (Scopus)

抄録

To elucidate the pressure evolution of the electronic structure in an antiferromagnetic dimer-Mott (DM) insulator β′-(BEDT-TTF)2ICl2, which exhibits superconductivity at 14.2 K under 8 GPa, we measured the polarized infrared (IR) optical spectra under high pressure. At ambient pressure, two characteristic bands due to intra- and interdimer charge transfers have been observed in the IR spectra, supporting that this salt is a typical half-filled DM insulator at ambient pressure. With increasing pressure, however, the intradimer charge transfer excitation shifts to much lower energies, indicating that the effective electronic state changes from half-filled to 3/4-filled as a result of weakening of dimerization. This implies that the system approaches a charge-ordered state under high pressure, in which charge degrees of freedom emerge as an important factor. The present results suggest that charge fluctuation inside of dimers plays an important role in the high-temperature superconductivity.

本文言語English
論文番号085149
ジャーナルPhysical Review B - Condensed Matter and Materials Physics
92
8
DOI
出版ステータスPublished - 2015 8 28
外部発表はい

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 凝縮系物理学

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