Charge ordering and coexistence of charge fluctuations in quasi-two-dimensional organic conductors $\theta$-(BEDT-TTF)${}_{2}X$

Abstract

We present a scenario for the peculiar coexistence of charge fluctuations observed in quasi-2D 1/4-filled organic conductors $\theta$-(BEDT-TTF)${}_{2}X$ in the quantum critical regime where the charge ordering is suppressed down to zero temperature. The scenario is explored in the extended Hubbard model including electron-phonon couplings on an anisotropic triangular lattice. We find that the coexisting fluctuations emerge from two different instabilities, the ``Wigner crystallization on lattice'' driven by the off-site Coulomb repulsion and the charge-density-wave formation due to the nesting of the Fermi surface, not from phase competition or real-space inhomogeneity. This mechanism explains the contrastive temperature dependence of two fluctuations in experiments.

4 pages, 3 figures

References in corpus (4)

• 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
• Novel Charge Order and Superconductivity in Two-Dimensional Frustrated Lattice at Quarter Filling
• The Origin of the Charge Ordering and Its Relevance to Superconductivity in $\theta$-(BEDT-TTF)${}_2$X: The Effect of the Fermi Surface Nesting and the Distant Electron-Electron Interactions

Cited by in corpus (2)

• Coexistence of distinct charge fluctuations in $\theta$-(BEDT-TTF)${}_2$X
• Variational Monte Carlo Study of a Spinless Fermion t-V Model on a Triangular Lattice: Formation of a Pinball Liquid