Related papers: Charge ordering and spin- Peierls transition in al…
We study a novel S=1/2 cluster chain Hamiltonian which has recently been proposed in the context of the charge ordered low-temperature phase of alpha'-NaV2O5. We perform a detailed investigation of this model within a large range of…
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…
We report the first observation of new lines in the infrared spectrum of a crystal due to unit-cell doubling at the spin-Peierls transition (in NaV_2O_5). The change in the shape of the spectral lines at the spin-Peierls transition is…
We propose a mechanism for the observed stacking charge order in the quarter-filled ladder compound NaV2O5. Via a standard mapping of the charge degrees of freedom onto Ising spins we explain the stacking order as a result of competition…
A huge increase of thermal conductivity k is observed at the phase transition in stoichiometric NaV2O5. This anomaly decreases and gradually disappears with deviation from stoichiometry in Na(1-x}V2O5 (x = 0.01, 0.02, 0.03, and 0.04). This…
We present results from magnetic resonance measurements for 75-350 GHz in $\alpha$'-NaV$_{2}$O$_{5}$. The temperature dependence of the integrated intensity indicates that we observe transitions in the excited state. A quantitative…
A possible ground state of NaV_2O_5 is proposed based on the Hartree approximation for both on-site and intersite Coulomb interactions. The results indicate that the intersite Coulomb interaction induces a zigzag type of charge…
We examine critically two different recently proposed models of charge ordering in the nominally 1/4-filled organic charge transfer solids (CTS). In one dimension, the two models are characterized by site charge densities of the form…
Dynamical properties of the novel inorganic spin-Peierls compound \alpha'--NaV2O5 are investigated using a one-dimensional dimerized Heisenberg model. By exact diagonalizations of chains with up to 28 sites, supplemented by a finite-size…
We present a theory of the anisotropy tuned quantum phase transition between spin nematic and spin-Peierls phases in S=1 systems with significant bi-quadratic exchange interactions. Based on quantum Monte Carlo studies on finite size…
(TMTTF)2AsF6 undergoes two phase transitions upon cooling from 300 K. At Tco=103 K a charge-ordering (CO) occurs, and at Tsp(B=9 T)=11 K the material undergoes a spin-Peierls (SP) transition. Within the intermediate, CO phase, the charge…
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…
Using spectral ellipsometry, we have measured the dielectric function of a Na$_{0.82(2)}$CoO$_2$ crystal that exhibits bulk antiferromagnetism with T$_{N}$=19.8 K. We identify two prominent transitions as a function of temperature. The…
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…
A spin-flip potential $V$ is introduced in a BCS Hamiltonian in order to study a possible thermodynamic effect that might be caused by the addition of a magnetic impurity in a superconductor. We found that the competition between the…
Recently, a Verwey-type transition in the mixed-valence alkali sesquioxide Cs$_4$O$_6$ was deduced from the charge ordering of molecular peroxide O$_2^{2-}$ and superoxide O$_2^-$ anions accompanied by the structural transformation and a…
We study \textit{ab initio} a pyrochlore compound, CsW$_{2}$O$_{6}$, which exhibits a yet unexplained metal-insulator transition. We find that (1) the reported low-$T$ structure is likely inaccurate and the correct structure has a twice…
The magnetic susceptibility of a new one-dimensional, S=1 system, the vanadium oxide LiVGe2O6, has been measured. Contrary to previous S=1 chains, it exhibits an abrupt drop at 22 K typical of a spin-Peierls transition, and it is consistent…
The present resonant x-ray scattering from each of monoclinically-split single domains of NaV2O5 has critically enhanced contrast between V4+ and V5+ ions strong enough to lead to unambiguous conclusion of the charge-order pattern of its…
We present the temperature dependence of shear and longitudinal elastic constants in a'-NaV2O5. For the longitudinal c22 and c33 modes we find anomalies at Tc in contrast to the Spin Peierls substance CuGeO3 where only the longitudinal mode…