Related papers: Charge and orbital order in Fe_3O_4
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…
We investigate the frustrated magnetic interactions in cubic transition metal oxides with orbital degeneracy. The $e_g$ orbitals order easier and their ordering explains the $A$-type antiferromagnetic phase in KCuF$_3$ and LaMnO$_3$. In…
The candidate magnetoelectric Pb3Mn7O15 has a structure consisting of 1/3 filled Kagome layers linked by ribbons of edge-sharing octahedra in the stacking direction. Previous reports have indicated a complex hexagonal-orthorhombic…
Here we show that the 2.80(8) {\mu}B/Fe block antiferromagnetic order of BaFe2Se3 transforms into stripe antiferromagnetic order in KFe2Se3 with a decrease in moment to 2.1(1) {\mu}B/Fe. This reduction is larger than expected from the…
We investigate spin-charge-orbital ordering in a Mn$^{3+}$/Mn$^{4+}$ mixed valence state on a hollandite-type lattice using unrestricted Hartree-Fock calculation on a multi-band Mn 3$d$-O 2$p$ lattice model. The calculations show that the…
We report a high-resolution neutron diffraction study of the crystal and magnetic structure of the orbitally-degenerate frustrated metallic magnet AgNiO2. At high temperatures the structure is hexagonal with a single crystallographic Ni…
We present the results of a systematic x-ray scattering study of the charge and orbital ordering in the manganite series Pr$_{1-x}$Ca$_x$MnO$_3$ with $x$=0.25, 0.4 and 0.5. The temperature dependence of the scattering at the charge and…
The magnetic ordering of La$_{1/3}$Sr$_{2/3}$FeO$_3$ perovskite has been studied by neutron powder diffraction and $^{57}$Fe M\"ossbauer spectroscopy down to 2 K. From symmetry analysis, a chiral helical model and a collinear model are…
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…
Based on density functional calculations, we propose a possible orbital ordering in MnV2O4 which consists of orbital chains running along crystallographic a and b directions with orbitals rotated alternatively by about 45 degrees within…
A partial disorder on a layered triangular lattice is theoretically investigated from a viewpoint of toroidal ordering and magnetoelectric effects. We consider an extended periodic Anderson model including a site-dependent antisymmetric…
We discuss a new mechanism of orbital ordering, which in charge transfer insulators is more important than the usual exchange interactions and which can make the very type of the ground state of a charge transfer insulator, i.e. its orbital…
We study the charge ordering behavior under a magnetic field $H$ in the extended Hubbard model within the coherent potential approximation. At quarter filling, for small $H$ we find that the relative variation of critical temperature is…
Ground state of the periodic Anderson model on a cubic lattice is investigated by mean-field calculations, with focusing on the possibility of charge ordering. We show that three different charge-ordered phases appear at 3/2 filling, which…
The apparent contradiction between the recently observed weak charge disproportion and the traditional Mn$^{3+}$/Mn$^{4+}$ picture of the charge-orbital orders in half-doped manganites is resolved by a novel Wannier states analysis of the…
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…
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…
Neutron diffraction measurements on multiferroic LuFe2O4 show changes in the antiferromagnetic (AFM) structure characterized by wavevector q = (1/3 1/3 1/2) as a function of electric field cooling procedures. The increase of intensity from…
Motivated by recent structural data questioning the adequacy of the charge order (CO)/disorder picture for the Verwey transition (at T=T_V) in magnetite, we re-investigate this issue within a new theoretical picture. Using the…
We investigate the effects of the $\sqrt{5}\times\sqrt{5}$ Fe vacancy ordering on the orbital and magnetic order in (K,Tl,Cs)$_y$Fe$_{2-x}$Se$_2$ using a three-orbital ($t_{2g}$) tight-binding Hamiltonian with generalized Hubbard…