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arXiv · 0810.2536

Spin and Charge Fluctuations and Lattice Effects on Charge Orders in α-(BEDT-TTF)_2I_3

Satoshi Miyashita·Kenji Yonemitsu
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Abstract

The effects of spin and charge fluctuations and electron-phonon couplings on charge ordering in α-(BEDT-TTF)_2I_3 (BEDT-TTF=bis(ethylenedithio)-tetrathiafulvalence) are investigated theoretically for an anisotropic triangular lattice at 3/4 filling. By the exact-diagonalization method, we have calculated the hole density distributions and the modulations of transfer integrals from high-temperature values as a function of electron-phonon coupling strength. The results clearly show that the lattice effect on α-(BEDT-TTF)_2I_3 is weak compared with that on θ-(BEDT-TTF)_2RbZn(SCN)_4, as previously found by experiments. This finding, which is also consistent with recent mean-field results, is systematically explained by strong-coupling perturbation theory; the effects of spin fluctuations are partially canceled by charge fluctuations in α-(BEDT-TTF)_2I_3.

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Satoshi Miyashita, Kenji Yonemitsu. 2008-10-14. Spin and Charge Fluctuations and Lattice Effects on Charge Orders in α-(BEDT-TTF)_2I_3. https://doi.org/10.1143/jpsj.77.094712

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