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

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.

arXiv comment14 pages, 5 figures

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Cited by in corpus (8)

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• Purely electronic THz polarization in dimer Mott insulators
• Charge, Lattice, and Spin Dynamics in Photoinduced Phase Transitions from Charge-Order-Insulator to Metal in Quasi-Two-Dimensional Organic Conductors
• Correlation Effects on Charge Order and Zero-Gap State in the Organic Conductor α-(BEDT-TTF)2I3
• Photoinduced Enhancement of Anisotropic Charge Correlations on Triangular Lattices with Trimers
• Effects of Lattice and Molecular Phonons on Photoinduced Neutral-to-Ionic Transition Dynamics in Tetrathiafulvalene-$p$-Chloranil