title: Optical conductivity measurement of a dimer Mott-insulator to charge-order phase transition in a two-dimensional quarter-filled organic salt compound.
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 Tc, suggesting a nature of quantum phase transition driven by material-parameter variations.
authors: Department of Physics, Nagoya University, Nagoya 464-8602, Japan.
authors: Ryuji
authors: R
authors: Okazaki
authors: Yuka
authors: Y
authors: Ikemoto
authors: Taro
authors: T
authors: Moriwaki
authors: Takahisa
authors: T
authors: Shikama
authors: Kazuyuki
authors: K
authors: Takahashi
authors: Hatsumi
authors: H
authors: Mori
authors: Hideki
authors: H
authors: Nakaya
authors: Takahiko
authors: T
authors: Sasaki
authors: Yukio
authors: Y
authors: Yasui
authors: Ichiro
authors: I
authors: Terasaki