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Charge ordering in theta-(BEDT-TTF)_2 X materials

R. T. Clay·S. Mazumdar·D. K. Campbell
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Abstract

We investigate theoretically charge ordered states on the anisotropic triangular lattice characteristic of the theta-(BEDT-TTF)_2 X materials. Using exact diagonalization studies, we establish that the charge order (CO) pattern corresponds to a ``horizontal'' stripe structure, with ...1100... CO along the two directions with larger electron hopping (p-directions), and ...1010... CO along the third direction (c-direction). The CO is accompanied by co-operative bond dimerizations along all three directions in the highest spin state. In the lowest spin state bonds along the p-directions are tetramerized. Our theory explains the occurence of a charge-induced high temperature transition as well as a spin gap transition at lower temperature.

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R. T. Clay, S. Mazumdar, D. K. Campbell. 2002-03-12. Charge ordering in theta-(BEDT-TTF)_2 X materials. https://doi.org/10.1143/jpsj.71.1816

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