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Ferroelectric phase transition, ionicity condensation, and multicriticality in charge transfer organic complexes

Jun-ichiro Kishine·Tadeusz Luty·Kenji Yonemitsu
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Abstract

To elucidate a novel pressure-temperature phase diagram of the quasi-one-dimensional mixed-stack charge-transfer (CT) complex TTF-CA, we study the quasi-one-dimensional spin-1 Blume-Emery-Griffith (BEG) model. In addition to the local charge transfer energy and the inter-stack polar (dipole-dipole) interaction, we take account of the inter-stack electrostriction effect. 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 (I$_{\rm{para}}$), and ferroelectric ionic (I$_{\rm{ferro}}$) phases, respectively. We also give an explanation on the experimentally observed multicritical behavior and concomitant discontinuous inter-stack lattice contraction in TTF-CA.

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Jun-ichiro Kishine, Tadeusz Luty, Kenji Yonemitsu. 2003-07-30. Ferroelectric phase transition, ionicity condensation, and multicriticality in charge transfer organic complexes. https://doi.org/10.1103/physrevb.69.075115

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