We report on the influence of the lattice degrees of freedom on charge, orbital and spin correlations in colossal magnetoresistance (CMR) manganites. For the weakly doped compounds we demonstrate that the electron-phonon coupling promotes the trapping of charge carriers, the disappearance of the orbital polaron pattern and the breakdown of ferromagnetism at the CMR transition. The role of diffe...

model the covalency-mixing parameters, λσ and λπ, the electron spin transfer coefficients, ƒi (i=σ, π, s ), and the total charge, C, transferred from ligand to the chromium ions, are evaluated. The variation of bσσ and bσπ with x agree with the passage of the system from ferromagnetic to antiferromagnetic order. For the compound presenting re-entrant behaviour ( 58 . 0 45 . 0 ≤ ≤ x ), fs exhibi...

A spinless Bose-Hubbard model in a one-dimensional (1D) double-chain tilted lattice is numerically studied at unit filling per cell. When each atom localized two-site cell, the low-energy effective gives rise to an exact textbook of 1D transverse Ising via superexchange interaction. To validate model, we calculate energy spectrum and nearest-neighbor correlation functions states subspace which ...

Basic mechanisms controlling orbital order and orbital fluctuations in transition metal oxides are discussed. The lattice driven classical orbital picture, e.g. like in manganites LaMnO3, is contrasted to the quantum behavior of orbitals in frustrated superexchange models as realised in pseudocubic titanites ATiO3 and vanadates AVO3. In YVO3, the lattice and superexchange effects strongly compe...

A spin-boson model based on local pseudo-spins acting in the electronic occupation number space is suggested and used to describe the thermally activated interelectrode current through a molecular wire. Utilizing the density matrix technique a unified description is achieved of all those kinetic processes which contribute to the inelastic current formation. These processes cover a specific supe...