Correlation Effects on Charge Order and Zero-Gap State in the Organic Conductor α-(BEDT-TTF)2I3
arXiv:1609.01433 · doi:10.7566/JPSJ.85.104706
Abstract
The effects of electron correlation in the quasi-two-dimensional organic conductor α-(BEDT-TTF)2I3 are investigated theoretically by using an extended Hubbard model with on-site and nearest-neighbor Coulomb interactions. A variational Monte Carlo method is applied to study its ground-state properties. We show that there appears a nonmagnetic horizontal-stripe charge order in which nearest-neighbor correlation functions indicate a tendency toward a spin-singlet formation on the bonds with large transfer integrals along the charge-rich stripe. Under uniaxial pressure, a first-order transition from the nonmagnetic charge order to a zero-gap state occurs. Our results on a spin correlation length in the charge-ordered state suggest that a spin gap is almost unaffected by the uniaxial pressure in spite of the suppression of the charge disproportionation. The relevance of these contrasting behaviors in spin and charge degrees of freedom to recent experimental observations is discussed.
15 pages, 9 figures, accepted for publication in J. Phys. Soc. Jpn
References in corpus (10)
- Tilted anisotropic Dirac cones in quinoid-type graphene and alpha-(BEDT-TTF)_2I_3
- Charge Ordering in alpha-(BEDT-TTF)2I3 by synchrotron x-ray diffraction
- 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
- Electronic Properties Close to Dirac Cone in Two-Dimensional Organic Conductor -(BEDT-TTF)I
- Charge order and superconductivity in a two-dimensional triangular lattice at n=2/3
- Coexistence of distinct charge fluctuations in -(BEDT-TTF)X
- Renormalization Effects on Quasi-Two-Dimensional Organic Conductor α-(BEDT-TTF)2I3
- Spin and Charge Fluctuations and Lattice Effects on Charge Orders in α-(BEDT-TTF)_2I_3
- Quantitative expression of the spin gap via bosonization for a dimerized spin-1/2 chain