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Department of Theoretical Studies, Institute for Molecular Science, Okazaki 444-8585, Japan and Department of Functional Molecular Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan
Institute of Physical and Theoretical Chemistry, Technical University of Wrocaw, 50-370 Wrocaw, Poland
Department of Theoretical Studies, Institute for Molecular Science, Okazaki 444-8585, Japan and Department of Functional Molecular Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan
抄録
To elucidate a pressure-temperature phase diagram of the quasi-one-dimensional mixed-stack charge-transfer complex tetrathiafulvalene-P-chloranil (TTF-CA), we study the quasi-one-dimensional spin-1 Blume-Emery-Griffiths model. In addition to the local charge-transfer energy (Δ) and the inter-stack polar (dipole-dipole) interaction (J), we take account of the interstack electrostriction (Coulomb-lattice coupling). Using the self-consistent chain-mean-field theory, where the intra-stack degrees of freedom are exactly treated by the transfer-matrix method, we reproduce the gas-liquid-solid like phase diagram corresponding to the neutral (N), paraelectric ionic (Ipara), and ferroelectric ionic (Iferro) phases, respectively. Our classical model describes an essential point of the multicritical behavior of TTF-CA, i.e., the interchain electrostriction exclusively enhances the charge concentration (ionicity condensation), but does not affect the interchain ferroelectric coupling. This effect leads to appearance of the intermediate Ipara phase in between the N and Iferro phases on the -T phase diagram.
雑誌名
Physical review B. Condensed matter and materials physics
巻
69
号
7
ページ
075115-1 - 075115-5
発行年
2004-02-27
出版者
Published by the American Physical Society through the American Institute of Physics
Ferroelectric phase transition, ionicity condensation, and multicriticality in charge-transfer organic complexes
075115.pdf
(262.69KB)
