Related papers: Charge Ordering and Spin Dynamics in NaV2O5
We discuss magnetic excitations of a spin-cluster model which has been suggested to describe the low temperature phase of alpha'-NaV_2O_5. This model fulfills all symmetry criteria proposed by recent x-ray investigations. We find that this…
Ab initio band theory including correlations due to intra-atomic repulsion is applied to study charge disproportionation and charge- and spin-ordering in insulating Na$_{0.5}$CoO$_2$. Various ordering patterns (zigzag and two striped) for…
Neutron scattering experiments were performed on single crystals of layered cobalt-oxides La2-xCaxCoO4 (LCCO) to characterize the charge and spin orders in a wide hole-doping range of 0.3<x<0.8. For a commensurate value of x=0.5 in (H,0,L)…
The low energy spin excitations of La(2-x)Sr(x)NiO(4), x = 0.275 and 1/3, have been investigated by unpolarized- and polarized-inelastic neutron scattering from single crystals. A pattern of magnetic diffuse scattering is observed in both…
We have investigated the charge and spin ordering in Nd{1/3}Sr{2/3}FeO{3} with neutron diffraction technique. This sample undergoes a charge ordering transition accompanying charge disproportionation of 2Fe4+ -> Fe3+ + Fe5+. We measured the…
We investigate magnetic excitations in the frustrated zigzag spin-1/2 chain compound $\beta$-TeVO$_4$ by inelastic neutron scattering. In the magnetically ordered ground state, the excitation spectrum exhibits coexisting magnon dispersion,…
We present the measurements of the polarized optical spectra of NaV2O5 and LiV2O5. In an energy range from 0.5 to 5.5 eV we observe similar peaks in the E parallel a spectra of LiV2O5 and NaV2O5, which suggests similar electronic structure…
The relationships among charge order, spin fluctuations, and superconductivity in underdoped cuprates remain controversial. We use neutron scattering techniques to study these phenomena in La$_{1.93}$Sr$_{0.07}$CuO$_4$, a superconductor…
We show that the asymmetric crystal environment of the V site in the ladder compound NaV$_{2}$O$_{5}$ leads to a strong coupling of vanadium 3d electrons to phonons. This coupling causes fluctuations of the charge on the V ions, and favors…
Many low dimensional spin systems with a dimerized or ladder-like antiferromagnetic exchange coupling have a gapped excitation spectrum with magnetic bound states within the spin gap. For spin ladders with an even number of legs the…
A systamatic quantitative comparison of ''pseudogap'' values obtained from the analysis of charge and spin excitation spectroscopies in underdoped YBa2Cu3O7-x using a temperature-independent gap shows two distinct excitations, one visible…
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 present an inelastic neutron scattering investigation of Li2CuO2 detecting the long sought quasi-1D magnetic excitations with a large dispersion along the CuO2-chains studied up to 25 meV. The total dispersion is governed by a…
We have studied magnetic correlations in several compositions of stripe-ordered La2-xSrxNiO4. In this paper we show how polarized-neutron scattering has helped uncover important features of the magnetic ordering and spin dynamics. In…
The results of 13C NMR spectra and nuclear spin-lattice relaxation rate 1/T_1 for the quasi-one-dimensional quarter-filled organic material (TMTTF)2SCN are presented. A new inhomogeneous line appears below the anion ordering temperature…
We present elastic and quasielastic neutron scattering measurements characterizing peculiar short-range charge-orbital and spin order in the layered perovskite material La1.5Sr0.5CoO4. We find that below Tc~750 K holes introduced by Sr…
The nature of electronic states due to strong correlation and geometric frustration on the triangular lattice is investigated in connection to the unconventional insulating state of Na$_x$CoO$_2$ at $x=0.5$. We study an extended Hubbard…
An exact-diagonalization technique on small clusters is used to calculate the dynamical density correlation functions of the dimerized t-J chain and coupled anisotropic t-J ladders (trellis lattice) at quarter filling, i.e., the systems…
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…
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…