Related papers: Electronic State of Na_xCoO_2 Based on the Two Dim…

The electronic structures, charge and spin dynamics of the cobalt pnictide compounds ACo2As2 (A=Ba, Sr, Ca) in the paramagnetic state are investigated by using density functional theory combined with dynamical mean-field theory. In contrast…

Qian et al [1] recently reported angular-resolved photoemission spectroscopy (ARPES) measurements for Na0.8CoO2 that show two concentric Fermi surfaces (FS) split by a delta k_F that varies by a factor of three around the Brillouin zone…

The possibility of charge order is theoretically examined for the Kondo lattice model in two dimensions, which does not include bare repulsive interactions. Using two complementary numerical methods, we find that charge order appears at…

We study the effects of the Coulomb interaction in the one dimensional Kondo lattice model on the phase diagram, the static magnetic susceptibility and electron spin relaxation. We show that onsite Coulomb interaction supports ferromagnetic…

Puzzling properties of sodium cobaltates Na${}_x$CoO${}_2$ become an issue of numerous recent theoretical and experimental investigations because of very high thermopower and intricate phase diagram of this material. Experiments indicated…

The determination by powder neutron diffraction of the ambient temperature crystal structures of compounds in the NaxCoO2 family, for 0.3 < x <= 1.0, is reported. The structures consist of triangular CoO2 layers with Na ions distributed in…

Motivated by the recent discovery of superconductivity in Na$_x$CoO$_2\cdot y$H$_2$O, we use series expansion methods and cluster mean-field theory to study spontaneous charge order, Neel order, ferromagnetic order, dimer order and…

The strength and effect of Coulomb correlations in the (superconducting when hydrated) x~1/3 regime of Na(x)CoO(2) have been evaluated using the correlated band theory LDA+U method. Our results, neglecting quantum fluctuations, are: (1)…

We study a one-dimensional extended Hubbard model with longer-range Coulomb interactions at quarter-filling in the strong coupling limit. We find two different charge-ordered (CO) ground states as the strength of the longer range…

We have studied the electronic properties of the ladder compound $\alpha'$-NaV$_{2}$O$_{5}$, adopting a joint experimental and theoretical approach. The momentum-dependent loss function was measured using electron energy-loss spectroscopy…

We consider possible routes to superconductivity in hydrated cobaltates Na_xCoO_2.yH_2O on the basis of the t-J-V model plus phonons on the triangular lattice. We studied the stability conditions for the homogeneous Fermi liquid (HFL) phase…

Starting from {\it ab-initio} band structure for Na$_x$CoO$_2$, we derive the single-electron energies and the effective tight-binding description for the $t_{2g}$ bands using a projection procedure. We find that due to the presence of the…

With a treatment of the 4$f$ states of EuB$_6$ based on LDA+U method, the mixing of Eu $f$ states with B $p$ states around the X point of the Brillouin zone is shown to have unexpected consequences for the effective exchange interactions.…

The CoO$_{2}$ layers in sodium-cobaltates Na$_{x}$CoO$_{2}$ may be viewed as a spin $S=1/2$ triangular-lattice doped with charge carriers. The underlying physics of the cobaltates is very similar to that of the high $T_{c}$ cuprates. We…

The t2g quasi-particle spectra of Na_0.3CoO_2 are calculated within the dynamical mean field theory. It is shown that as a result of dynamical Coulomb correlations charge is transfered from the nearly filled e_g' subbands to the a_1g band,…

We study the electronic structure of Ca2-xNaxCuO2Cl2 and Bi2Sr2CaCu2O8+d samples in a wide range of doping, using angle-resolved photoemission spectroscopy, with emphasis on on the Fermi surface (FS) in the near anti-nodal region. The…

We systematically analyze the influence of the superconducting gap symmetry and the electronic structure on the dynamical spin susceptibility in superconducting Na_xCoO_2$\cdot y$H_2O within a three different models: the single a_{1g}-band…

Using the Lanczos exact-diagonalization and density-matrix renormalization group methods, we study the extended Hubbard model at quarter filling defined on the anisotropic triangular lattice. We focus on charge ordering (CO) phenomena…

We model electronic properties of the second monolayer Na adatom islands (quantum dots) on the Cu(111) surface covered homogeneously by the first Na monolayer. An axially-symmetric three-dimensional jellium model, taking into account the…

In strongly correlated systems the strength of Coulomb interactions between electrons, relative to their kinetic energy, plays a central role in determining their emergent quantum mechanical phases. We perform resonant x-ray scattering on…