16,541 research outputs found
Novel Charge Order and Superconductivity in Two-Dimensional Frustrated Lattice at Quarter Filling
Motivated by the various physical properties observed in
-(BEDT-TTF)X, we study the ground state of extended Hubbard model
on two-dimensional anisotropic triangular lattice at 1/4-filling with
variational Monte Carlo method. It is shown that the nearest-neighbor Coulomb
interaction enhances the charge fluctuation and it induces the anomalous state
such as charge-ordered metallic state and the triplet next-nearest-neighbor
-wave superconductivity. We discuss the relation to the real materials and
propose the unified view of the family of -(BEDT-TTF)X.Comment: 4 pages, 5 figure
Nonlinear Conduction by Melting of Stripe-Type Charge Order in Organic Conductors with Triangular Lattices
We theoretically discuss the mechanism for the peculiar nonlinear conduction
in quasi-two-dimensional organic conductors \theta-(BEDT-TTF)2X
[BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene] through the melting of
stripe-type charge order. An extended Peierls-Hubbard model attached to
metallic electrodes is investigated by a nonequilibrium Green's function
technique. A novel current-voltage characteristic appears in a coexistent state
of stripe-type and nonstripe 3-fold charge orders, where the applied bias melts
mainly the stripe-type charge order through the reduction of lattice
distortion, whereas the 3-fold charge order survives. These contrastive
responses of the two different charge orders are consistent with the
experimental observations.Comment: 5 pages, 4 figures, to appear in J. Phys. Soc. Jp
Quantum Melting of Charge Order due to Frustration in Two-Dimensional Quarter-Filled Systems
The effect of geometrical frustration in a two-dimensional 1/4-filled
strongly correlated electron system is studied theoretically, motivated by
layered organic molecular crystals. An extended Hubbard model on the square
lattice is considered, with competing nearest neighbor Coulomb interaction, V,
and that of next-nearest neighbor along one of the diagonals, V', which favor
different charge ordered states. Based on exact diagonalization calculations,
we find a metallic phase stabilized over a broad window at V' ~ V even for
large Coulomb repulsion strengths as a result of frustrating the charge ordered
states. Slightly modifying the lattice geometry relevant to the actual organic
compounds does not alter the results, suggesting that this `quantum melting' of
charge order is a robust feature of frustrated strongly correlated 1/4-filled
systems.Comment: 5 pages, 4 figures, to be published in Phys. Rev.
2-elementary subgroups of the space Cremona group
We give a sharp bound for orders of elementary abelian 2-groups of birational
automorphisms of rationally connected threefolds
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