Related papers: Successive Phase Transitions in Na_{0.5}CoO_{2} ba…
The influence of a nearest-neighbor Coulomb repulsion of strength V on the properties of the Ferromagnetic Kondo model is analyzed using computational techniques. The Hamiltonian studied here is defined on a chain using localized S=1/2…
We have synthesized and characterized different stable phases of sodium cobaltates Na$_{x}$CoO$_{2}$ with sodium content $0.65<x<0.80$. We demonstrate that $^{23}$Na NMR allows to determine the difference in the susceptibility of the phases…
Magnetic phase diagram for the Hubbard model on the Beta-Mn type lattice has been calculated as a function of the Coulomb interaction energy parameter U and the electron number per atom n by using the generalized Hartree-Fock approximation…
We study the effect of Coulomb interactions in transition metal oxides junctions. In this paper we analyze charge transfer at the interface of a three layer ferromagnetic-paramagnetic-ferromagnetic metallic oxide system. We choose a charge…
Phase transition in a honeycomb lattice is studied by the means of the two dimensional Hubbard model and the exact diagonalization dynamical mean field theory at zero temperature. At low energies, the dispersion relation is shown to be a…
We study the evolution of orbital patterns in ferromagnetic layered ruthenates due to the competition of Coulomb interactions, compressive c axis and orthorhombic distortions in the presence of a polarizing orbital field coupled to the…
Charge disproportionation (CD) and spin differentiation in Na$_{1/2}$CoO$_2$ are studied using the correlated band theory approach. The simultaneous CD and gap opening seen previously is followed through a first order charge…
To describe the metal insulator transition in the new oxide TlSr2CoO5 we investigate its electronic structure by LDA and model Hartree-Fock calculations. Within LDA we find a homogeneous metallic and ferromagnetic ground state, but when…
Na0.5CoO2 exhibits a metal-insulator transition at 53 K upon cooling. The nature of another transition at 88 K has not been fully clarified yet. We report the results of measurements of the electrical conductivity, the magnetic…
The electronic structure of the $(2\sqrt{2}\times\sqrt{2})R45^{\circ}$ O/Cu(001) system has been calculated using locally self-consistent, real space multiple scattering technique based on first principles. Oxygen atoms are found to perturb…
We determine the quantum phase diagram of the antiferromagnetic spin-1/2 XXZ model on the triangular lattice as a function of magnetic field and anisotropic coupling $J_z$. Using the density matrix renormalization group (DMRG) algorithm in…
The electronic structure of Na$_x$CoO$_2$ revealed by recent photoemission experiments shows important deviations from band theory predictions. The six small Fermi surface pockets predicted by LDA calculations have not been observed as the…
A general spin-state model and a qualitative physical picture have been proposed for a class of lately synthesized layered cobalt oxides (LCOs) by means of density functional calculations. As the plane corrugation of the cobalt-oxygen layer…
We present the results of measurements of the dc-magnetic susceptibility chi(T) and the 23Na-NMR response of Na_{0.70}CoO_{2} at temperatures between 50 and 340 K. The chi(T) data suggest that for T > 75 K, the Co ions adopt an effective…
We study the competition between long-range and short-range interactions among holes within the spin density wave picture of layered transition metal oxides. We focus on the problem of charge ordering and the charge phase diagram. We show…
We study the topological phase transitions induced by Coulomb engineering in three triangular-lattice Hubbard models $AB_2$, $AC_3$ and $B_2C_3$, each of which consists of two types of magnetic atoms with opposite magnetic moments. The…
We report the results of low-temperature thermal and magnetic measurements on Ba$_3$CoNb$_2$O$_9$ powder, described as a uniform triangular-lattice antiferromagnet (TLAF) with a fictitious spin-1/2. Ba$_3$CoNb$_2$O$_9$ is found to undergo…
We study the physics on the paramagnetic side of the phase diagram of the cobaltates, $Na_{x}CoO_{2}$, with an implementation of cellular dynamical mean field theory (CDMFT) with the non-crossing approximation (NCA) for the one-band Hubbard…
We study theoretically the electronic states in a $5d$ transition metal oxide Na$_2$IrO$_3$, in which both the spin-orbit interaction and the electron correlation play crucial roles. Tight-binding model analysis together with the…
The investigation of electronic order-quantum phase interplay in kagome lattices commonly employs the extended Kagome-Hubbard model, where the critical parameters comprise on-site $(U)$ and intersite $(V)$ Coulomb interactions. In…