Related papers: A Model Study of the Low-Energy Charge Dynamics of…
Based on recent experimental evidences that the electronic charge degrees of freedom plays an essential role in the spin-Peierls--like phase transition of NaV$_2$O$_5$, we first make the mapping of low-energy electronic states of the…
The charge ordering transition in the layer compound NaV2O5 is studied by means of exact diagonalization methods for finite systems. The 2-leg ladders of the V-Trellis lattice are associated with one spin variable of the vanadium…
Optical conductivity of the trellis lattice t-J model at quarter filling is calculated by an exact-diagonalization technique on small clusters, whereby the valence state of V ions of NaV_2O_5 is considered. We show that the experimental…
Using finite temperature diagonalization techniques it is shown that the quarter-filled t-J-V model on a trellis lattice structure provides a quantitative explanation of the highly anisotropic optical conductivity of the…
We present Density Matrix Renormalization Group calculations of the ground-state properties of quarter-filled ladders including static electron-lattice coupling. Isolated ladders and two coupled ladders are considered, with model parameters…
An exact-diagonalization technique on small clusters is used to study the ground state of the dimerized t-J model at quarter filling. The equal-time charge and spin correlations, charge and spin gaps, and binding energy are calculated for…
Charge and spin-Peierls instabilities in quarter-filled (n=1/2) compounds consisting of coupled ladders and/or zig-zag chains are investigated. Hubbard and t-J models including local Holstein and/or Peierls couplings to the lattice are…
We investigate charge ordering in the presence of electron-phonon coupling for quarter-filled ladder systems by using Exact Diagonalization. As an example we consider NaV2O5 using model parameters obtained from first-principles…
The nature of insulating state driven by electronic correlations in the quarter-filled ladder compound $\alpha'$NaV$_{2}$O$_{5}$ is investigated within a cluster dynamical mean-field approach. An extended Hubbard model with first-principle…
The layered perovskite compound NaV_2O_5 exhibits charge ordering (CO) and spin gap formation which is driven by inter- site Coulomb forces and exchange dimerisation. Experimentally it was found that the CO transition is rapidly reduced by…
We investigate weakly coupled quarter-filled ladders with model parameters relevant for NaV_2O_5 using density-matrix renormalization group calculations on an extended Hubbard model coupled to the lattice. NaV2O5 exhibits…
Expressions for generalized charge stiffness constant at zero temperature are derived corresponding to low dimensional hole doped quantum antiferromagnets, describable by the t-J-like models, with a view to understanding fermionic pairing…
Motivated by Resonant X-ray scattering experiments in cuprate ladder materials showing charge order modulation of period $\lambda=3$ and 5 at specific hole densities, we investigate models involving the electronic t-J ladders and bosonic…
We argue that in the quarter-filled ladder compound NaV_2O_5 the quasi-one-dimensional spin system is strongly coupled to a low-energy antiferroelectric mode of the excitonic type. This mode results from the interplay between the electron…
Starting from the proper charge transfer model for Cu$_2$O$_5$ coupled ladders in Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$ we derive the low energy Hamiltonian for this system. It occurs that the widely used ladder t-J model is not sufficient and…
The spin and charge excitations of the t--J ladder are studied by exact diagonalization techniques for several electron densities. The various modes are classified according to their spin (singlet or triplet excitations) and their parity…
We present an exact diagonalization study of the dynamical spin and density correlation functions in small clusters of 2D t-J model for intermediate and low electron densities, rho<0.7. Both correlation functions agree remarkably well with…
The dynamical properties of an extended Hubbard model, which is relevant to quarter-filled layered organic molecular crystals, are analyzed. We have computed the dynamical charge correlation function, spectral density, and optical…
A theory of superexchange in the mixed valent layer compound NaV2O5 is presented which provides a consistent description of exchange both in the disordered and charge ordered state. Starting from results of band structure calculations for…
We analyze the electronic structure of a mixed-valence ladder system. We find that structural anisotropy and complex electron correlations lead to on-rung charge localization and insulating character. Charge fluctuations within the rung of…