Charge fluctuations in geometrically frustrated charge ordering system

Seo, Hitoshi; Tsutsui, Kenji*; Ogata, Masao*; Merino, J.*

Effects of geometrical frustration in low-dimensional charge ordering systems are theoretically studied, mainly focusing on dynamical properties. We treat extended Hubbard models at quarter-filling, where the frustration arises from competing charge ordered patterns favored by different intersite Coulomb interactions, which are effective models for various charge transfer-type molecular conductors and transition metal oxides. From previous studies, charge ordered insulating states are known to be unstable in the frustrated region, resulting in a robust metallic phase even when the interaction strenghs are strong. By applying the Lanczos exact diagonalization to finite-size clusters, we have found that fluctuations of different charge order patterns exist in the frustration-induced metallic phase, showing up as characteristic low energy modesin dynamical correlation functions.