相关论文: Universality in one dimensional orbital wave order…
It has been suggested that the metal-insulator transitions in a number of spinel materials with partially-filled t_2g d-orbitals can be explained as orbitally-driven Peierls instabilities. Motivated by these suggestions, we examine…
Dimension reduction due to the orbital ordering has recently been proposed to explain the exotic charge, magnetic and structural transitions in some three-dimensional (3D) transitional metal oxides. We present optical measurement on a…
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…
Mixed valence spinels provide a fertile playground for the interplay between charge, spin, and orbital degrees of freedom in strongly correlated electrons on a geometrically frustrated lattice. Among them, AlV$_2$O$_4$ and LiV$_2$O$_4$…
Evolution of composite spin-orbital order and coupled spin-orbital excitations is studied in a variety of $d^4$ systems with $n$=$4$ electrons in the $t_{2g}$ orbital sector using the generalised self-consistent + fluctuations approach for…
Motivated by recent experimental progress in transition metal oxides with the K$_2$NiF$_4$ structure, we investigate the magnetic and orbital ordering in $\alpha$-Sr$_2$CrO$_4$. Using first principles calculations, first we derive a…
We develop a microscopic theory for the charge ordering (CO) transitions in the spinels AlV$_2$O$_4$ and LiV$_2$O$_4$ (under pressure). The high degeneracy of CO states is lifted by a coupling to the rhombohedral lattice deformations which…
Recently, a Verwey-type transition in the mixed-valence alkali sesquioxide Cs$_4$O$_6$ was deduced from the charge ordering of molecular peroxide O$_2^{2-}$ and superoxide O$_2^-$ anions accompanied by the structural transformation and a…
The metal-insulator transition of the Magneli phase Ti4O7 is studied by means of augmented spherical wave (ASW) electronic structure calculations as based on density functional theory and the local density approximation. The results show…
We show that in transition metal compounds containing structural metal dimers there may exist in the presence of different orbitals a special state with partial formation of singlets by electrons on one orbital, while others are effectively…
In this work we apply the density matrices approach to orbital ordering (OO) in order to study the OO of the spinel vanadates AV$_{2}$O$_{4}$ (A $\equiv$ Zn, Cd and Mg), which is normally believed to be responsible for the structural…
We present a unique study of the frustrated spinel MgV2O4 which possesses highly coupled spin, lattice and orbital degrees of freedom. Using large single-crystal and powder samples, we find a distortion from spinel at room temperature…
In view of recent controversy regarding the orbital order in the frustrated spinel ZnV2O4, we analyze the orbital and magnetic groundstate of this system within an ab initio density functional theory approach. While LDA+U calculations in…
Charge ordering in the low-temperature triclinic structure of titanium oxide (Ti4O7) is investigated using the local density approximation (LDA)+U method. Although the total 3d charge separation is rather small, an orbital order parameter…
Using x-ray absorption spectroscopy at the Ru-$L_{2,3}$ edge we reveal that the Ru$^{4+}$ ions remain in the $S$=1 spin state across the rare 4d-orbital ordering transition and spin-gap formation. We find using local spin density…
Charge density waves in transition metal dichalcogenides have been intensively studied for their close correlation with Mott insulator, charge-transfer insulator, and superconductor. VTe2 monolayer recently comes into sight because of its…
The semiconductor-semiconductor transition of La2RuO5 is studied by means of augmented spherical wave (ASW) electronic structure calculations as based on density functional theory and the local density approximation. This transition has…
We analyze electronic, magnetic, and structural properties of the spinel compound MgTi$_2$O$_4$ using the local density approximation+U method. We show how MgTi$_2$O$_4$ undergoes to a canted orbital-spin ordered state, where charge, spin…
Motivated by recent experimental evidence of charge order in the pseudogap phase of cuprates, we perform a variational analysis of charge-neutral, spin-singlet ordering in metals on the square lattice, using a wavefunction with double…
The low and high-temperature phases of V$_4$O$_7$ have been studied by \textit{ab initio} calculations. At high temperature, all V atoms are electronically equivalent and the material is metallic. Charge and orbital ordering, associated…