Related papers: Charge order and phase segregation in overdoped bi…
The magnetic and orbital orders for the bilayer manganites in the doping region $0.5 < x <1.0$ have been investigated from a model that incorporates the two $e_g$ orbitals at each Mn site, the inter-orbital Coulomb interaction and lattice…
The charge ordering in the bilayer manganite system La$_{2-2x}$Sr$_{1+2x}$Mn$_{2}$O$_{7}$ with $0.30 \le x \le 0.50$ has been studied by neutron diffraction. The charge order is characterized by the propagation vector parallel to the [1 0…
An explanation is given for the charge order, orbital order and insulating state observed in half-doped manganese oxides, such as Nd$_{1/2}$Sr$_{1/2}$MnO$_{3}$. The competition between the kinetic energy of the electrons and the magnetic…
We demonstrate that the half-doped bilayer manganite La_{1}Sr_{2}Mn_{2}O_{7} exhibits CE-type charge-ordered and spin-ordered states below $T_{N, CO}^A = 210$ K and below $T_{N}^{CE} \sim 145$ K, respectively. However, the volume fraction…
The three dimensional perovskite manganites in the range of hole-doping $x > 0.5$ are studied in detail using a double exchange model with degenerate $e_g$ orbitals including intra- and inter-orbital correlations and near-neighbour Coulomb…
Spin-charge-orbital ordered structures in doped layered manganites are investigated using an orbital-degenerate double-exchange model tightly coupled to Jahn-Teller distortions. In the ferromagnetic phase, unexpected diagonal stripes at…
A short introduction to the complex phenomena encountered in transition metal oxides with either charge or orbital or joint charge-and-orbital order, usually accompanied by magnetic order, is presented. It is argued that all the types of…
The phase diagram of half-doped manganite systems of formula A_{0.5}A'_{0.5}MnO_3 is investigated within a single-orbital model incorporating magnetic double-exchange and superexchange, together with intersite Coulomb and electron-lattice…
We show that in manganites close to half-doping novel non-bipartite magnetic phases appear due to the interplay between double exchange, superexchange and orbital ordering. In considerable part of the phase diagram the groundstate has a…
Motivated by the recent ARPES measurements (Evtushinsky et. al., PRL {\bf 105}, 147201 (2010)) and evidence for the density-wave state for the charge and orbital ordering (Garc\'{i}a et al., PRL {\bf 109}, 107202 (2012)) in…
Correlation between orbital structure and magnetic ordering in bilayered manganites is examined. A level separation between the $3d_{3z^2-r^2}$ and $3d_{x^2-y^2}$ orbitals in a Mn ion is calculated in the ionic model for a large number of…
Based on the Hamiltonian of small polarons with the strong nearest neighbor repulsion, we have investigated the charge ordering phenomena observed in half-doped manganites R_{1/2}A_{1/2}MnO_3. We have explored possible consequences of the…
We derive an effective Hamiltonian that takes into account the quantum nature of phonons and models cooperative Jahn-Teller effect in the adiabatic regime and at strong electron-phonon coupling in one dimension. Our approach involves…
The orbital shapes and charge disproportionations at nominal Mn$^{3+}$ and Mn$^{4+}$ sites for the charge- and orbital-ordered phases have been studied on half-doped manganites Pr(Sr$_{0.1}$Ca$_{0.9}$)$_2$Mn$_2$O$_7$ and…
The crystallographic and magnetic phase diagram of the n=2 layered manganite La2-2xSr1+2xMn2O7 in the region x=>0.5 has been studied using temperature dependent neutron powder diffraction. The magnetic phase diagram reveals a progression of…
We present a mean-field theory of charge, orbital, and spin ordering in manganites at 50% and 0% dopings by considering Jahn-Teller interaction, nearest-neighbor repulsion, and no single-site double occupancy. For spinless fermions, we show…
Using first principle band structure calculations, we critically examine results of resonant x-ray scattering experiments which is believed to directly probe charge and orbital ordering. Considering the specific case of La0.5Sr1.5MnO4, we…
A simple model of charge ordering is considered. It is shown explicitly that at any deviation from half-filling ($n \neq 1/2$) the system is unstable with respect to phase separation into charge ordered regions with $n = 1/2$ and metallic…
We investigate the high temperature phase of layered manganites, and demonstrate that the charge-orbital phase transition without magnetic order in La$_{0.5}$Sr$_{1.5}$MnO$_4$ can be understood in terms of the density wave instability. The…
In the manganite Nd0.5Ca0.5MnO3, charge ordering occurs at much higher temperature than the antiferromagnetic order (TCO=250K,TN=160K). The magnetic behavior of the phase TN<T<TCO is puzzling: its magnetization and susceptibility are…