擬一次元曲面物質における光励起キャリアダイナミクス

抄録

Photo- or electron beam (EB) irradiation of C₆₀ results in various cross-linkages with various dimensionalities. One characteristic example of such coalesced structures is the one-dimensional (1D) peanut-shaped C₆₀ polymer reviewed by J.O. in another article. This EB-irradiated C₆₀ polymer exhibits a Fermi-edge anomaly in the valence band spectrum, showing a similarity to those observed in quasi-1D conductors. In this article, we demonstrate the photo-induced carrier dynamics of EB-irradiated C₆₀ polymer by utilizing an ultrafast optical spectroscopy. We first present an overview of the carrier dynamics in typical quasi-1D conductors, and then compare the properties with those of the EB-irradiated C₆₀ polymer. We also compare the carrier dynamics in the C₆₀ polymer and pristine samples, and show that the polymer sample exhibits an additional slow relaxation component below T∼60K. This component is similar to the interband relaxation observed in quasi-1D conductors below Peierls transition temperature, whereas the temperature dependence of the relaxation time exhibits no critical divergence that accounts for coherent gap formation. We will discuss the plausible origin.