J. Phys. IV France 12 (2002) Pr9-233
Unusual 2 k CDW state with enhanced charge ordering in P-(BEDT-TTF) AsF and PF6Y. Nogami1 and T. Mori2
1 Department of Physics, Okayama University, 3-1-1 Tsushimanaka, Okayama 700-8530, Japan
2 Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Okayama, Tokyo 152-8552, Japan
X-ray superstructure analyses of the CDW states for two-dimensional organic compounds -(BEDT-TTF) 2PF 6 and AsF 6 were presented Molecular ionicity of BEDT-TTF was evaluated with both intramolecular bond lengths and molecular shape. Strong bending of quasi-neutd BEDT-TTF molecules coupled with the enhanced amplitude of charge modulation was observed Conformational ordering of the terminal ethylenes of BEDT-TTF molecules anddmeriiation between quasi-ionic BEJYI-TTF molecules were also observed These characteristic indicates this CDW is not Peierls-Frohlich type but mupled with the internal degree of the molecular shape and possibly the intersite Coulomb repulsion.
© EDP Sciences 2002