Optical conductivity measurement of a dimer Mott-insulator to charge-order phase transition in a two-dimensional quarter-filled organic salt compound

Ryuji Okazaki, Yuka Ikemoto, Taro Moriwaki, Takahisa Shikama, Kazuyuki Takahashi, Hatsumi Mori, Hideki Nakaya, Takahiko Sasaki, Yukio Yasui, Ichiro Terasaki

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12 Citations (Scopus)

Abstract

We report a novel insulator-insulator transition arising from the internal charge degrees of freedom in the two-dimensional quarter-filled organic salt β-(meso-DMBEDT-TTF)2PF6. The optical conductivity spectra above Tc=70 K display a prominent feature of the dimer Mott insulator, characterized by a substantial growth of a dimer peak near 0.6 eV with decreasing temperature. The dimer peak growth is rapidly quenched as soon as a peak of the charge order appears below Tc, indicating a competition between the two insulating phases. Our infrared imaging spectroscopy has further revealed a spatially competitive electronic phase far below T c, suggesting a nature of quantum phase transition driven by material-parameter variations.

Original languageEnglish
Article number217801
JournalPhysical Review Letters
Volume111
Issue number21
DOIs
Publication statusPublished - 18 Nov 2013

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