Related papers: Doped orbitally-ordered systems: another case of p…
The relationship between orbital and spin degrees of freedom in the single-crystals of the hole-doped Pr$_{1-x}$Ca$_{1+x}$MnO$_4$, 0.3 $\leq$ $x$ $\leq$ 0.7, has been investigated by means of ac-magnetometry and charge transport. Even…
Using scaled-particle theory for binary mixtures of two-dimensional hard particles with rotational freedom, we analyse the stability of nematic phases and the demixing phase behaviour of a variety of mixtures, focussing on cases where at…
The two-orbital Hubbard model for the pnictides is studied numerically using the real-space Hartree-Fock approximation on finite clusters. Upon electron doping, states with a nonuniform distribution of charge are stabilized. The observed…
In a system where selective Mott localization is realized, some electrons show a gap to charge excitations while others do not. A hybridization between these two kind of electrons will lead to a smoothening of this sharp difference and can…
We study the occurence of delay mechanisms other than periodic orbits in systems with time dependent potentials that exhibit chaotic scattering. By using as model system two harmonically oscillating disks on a plane, we have found the…
The so-called method of phase synchronization has been advocated in a number of papers as a way of decoupling a system of linear second-order differential equations by a linear transformation of coordinates and velocities. This is a rather…
In the Mott insulating phase of the transition metal oxides, the effective orbital-orbital interaction is directional both in the orbital space and in the real space. We discuss a classical realization of directional coupling in two…
The phase diagram of a model describing doped CuGeO$_3$ is derived. The model emphasizes the role of local moments released by the impurities and randomly distributed inside the gaped singlet background. The phase diagram is investigated by…
Theory of dilution effect in orbital ordered system is presented. The $e_g$ orbital model without spin degree of freedom and the spin-orbital coupled model in a three-dimensional simple-cubic lattice are analyzed by the Monte-Carlo…
We analyze the symmetry changes of the paramagnetic to the A-type antiferromagnetic and to the ferromagnetic phase transitions in undoped and moderately doped LaMnO$_3$, respectively. We show that in the orthorhombic-distorted perovskite…
Phase separation can drive spatial organization of multicomponent mixtures. For instance in developing animal embryos, effective phase separation descriptions have been used to account for the spatial organization of different tissue types.…
We explore mechanisms of orbital order decay in doped Mott insulators $R_{1-x}$(Sr,Ca)$_x$VO$_3$ ($R=\,$Pr,Y,La) caused by charged (Sr,Ca) defects. Our unrestricted Hartree-Fock analysis focuses on the combined effect of random, charged…
The phase equilibrium in manganites under magnetic field is studied using a two orbital model, based on the equivalent chemical potential principle for the competitive phases. We focus on the magnetic field induced melting process of CE…
We attribute the structural phase transition (SPT) in the parent compounds of the iron pnictides to orbital ordering. Due to the anisotropy of the $d_{xz}$ and $d_{yz}$ orbitals in the $xy$ plane, a ferro-orbital ordering makes the…
We study the optical properties of semiconducting transition metal dichalcogenide monolayers under the influence of strong out-of-plane magnetic fields, using the effective massive Dirac model. We pay attention to the role of spin-orbit…
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…
We study the magnetic orbital effect of a doped two-leg ladder in the presence of a magnetic field component perpendicular to the ladder plane. Combining both low-energy approach (bosonization) and numerical simulations (density-matrix…
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…
The stripe phases found in correlated oxides can be viewed as an ordering of the solitons associated with doping the Mott-insulating state. Inspired by the recent observation that the stripes tilt away from the main axis of the crystal…
Effect of energetic disorder on charge carrier transport in organic materials has been reexamined. A reliable method for mobility calculation and subsequent evaluation of relevant disorder parameters has been discussed. This method is well…