相关论文: Orbital ordering and frustrations

We investigate the collective behavior of orbital angular momentum in the spin ferromagnetic state of a Mott insulator with $t_{2g}$ orbital degeneracy. The frustrated nature of the interactions leads to an infinite degeneracy of classical…

Spin correlations in metallic and insulating phases of $V_2O_3$ and its derivatives are investigated using magnetic neutron scattering. Metallic samples have incommensurate spin correlations varying little with hole doping. Paramagnetic…

The Jahn-Teller distortion and the resulting orbital order usually cause some fascinating correlated electronic behaviors, and generally lead to antiferromagnetism in perovskite bulks. Here we demonstrate that the Jahn-Teller distortion…

Magnetic systems governed by exchange interactions between magnetic moments harbor frustration that leads to ground state degeneracy and results in the new topological state often referred to as a frustrated state of matter (FSM). The…

The effective Hamiltonian for perovskite titanates is derived by taking into account the three-fold degeneracy of $t_{2g}$ orbitals and the strong electron-electron interactions. The magnetic and orbital ordered phases are studied in the…

Ordered mechanical systems typically have one or only a few stable rest configurations, and hence are not considered useful for encoding memory. Multistable and history-dependent responses usually emerge from quenched disorder, for example…

We propose a scenario for the two phase transitions in $A$V$_2$O$_4$ ($A$=Zn, Mg, Cd), based on an effective spin-orbital model on the pyrochlore lattice. At high temperatures, spin correlations are strongly frustrated due to the lattice…

The translational order in a three-dimensional lattice pinned by hopping defects is studied. It is suggested that the equilibrium state of the lattice crosses from a glass to a crystal on the rate of hopping. It is argued that such a…

Charge, spin, and orbital degrees of freedom underlie the physics of transition metal compounds. Much work has revealed quantum critical points associated with spin and charge degrees of freedom in many of these systems. Here we illustrate…

We investigate the interplay between Coulomb driven orbital order and octahedral distortions in strongly correlated Mott insulators due to orbital dilution, i.e., doping by metal ions without an orbital degree of freedom. In particular, we…

Besides magnetic and charge order, regular arrangements of orbital occupation constitute a fundamental order parameter of condensed matter physics. Even though orbital order is difficult to identify directly in experiments, its presence was…

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 present our theoretical results on the mechanism of two transitions in vanadium spinel oxides $A$V$_2$O$_4$ ($A$=Zn, Mg, or Cd) in which magnetic V cations constitute a geometrically-frustrated pyrochlore structure. We have derived an…

We investigate the phase diagrams of the spin-orbital $d^9$ Kugel-Khomskii model for increasing system dimensionality: from the square lattice monolayer, via the bilayer to the cubic lattice. In each case we find strong competition between…

We present the results of our theoretical study on the effects of geometrical frustration and the interplay between spin and orbital degrees of freedom in vanadium spinel oxides $A$V$_2$O$_4$ ($A$ = Zn, Mg or Cd). Introducing an effective…

Random quenched dilution of the triangular-lattice antiferromagnetic Ising model locally relieves frustration, leading to ordering phenomena. We have studied this system, under such dilution of one sublattice, using hard-spin mean-field…

We consider the impact of orbital polarons in doped orbitally ordered systems on optical conductivity using the simplest generic model capturing the directional nature of either $t_{2g}$ (or $e_g$) orbital states in certain transition metal…

The Jahn-Teller effect is a fascinating and ubiquitous phenomenon in modern quantum physics and chemistry. We propose a class of oxides with melilite structure Ba$_2$TGe$_2$O$_7$ (T=V,Ni) where Jahn-Teller distortions are the main…

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…

We report on first principles Self-Interaction Corrected LSD (SIC-LSD) calculations of electronic structure of LaMnO$_{3}$ in the cubic phase. We found a strong tendency to localisation of the Mn $e_{g}$ electron and to orbital ordering. We…