Spin and Charge Fluctuations and Lattice Effects on Charge Orders in α-(BEDT-TTF)_2I_3
arXiv:0810.2536 · doi:10.1143/JPSJ.77.094712
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.
14 pages, 5 figures
References in corpus (7)
- Charge Ordering in alpha-(BEDT-TTF)2I3 by synchrotron x-ray diffraction
- Theoretical Aspects of Charge Ordering in Molecular Conductors
- Strong coupling theory of the spinless charges on the triangular lattices: possibility of a new quantum liquid
- Quantum Melting of Charge Order due to Frustration in Two-Dimensional Quarter-Filled Systems
- Charge ordering in θ-(BEDT-TTF)2RbZn(SCN)4: Cooperative effects of electron correlations and lattice distortions
- Effects of Electron-Lattice Coupling on Charge Order in θ-(ET)2X
- Temperature-driven transition from the Wigner Crystal to the Bond-Charge-Density Wave in the Quasi-One-Dimensional Quarter-Filled band