Related papers: Temperature effects in a spin-orbital model for ma…
A detailed study of the electric field gradient (EFG) across the Pr1-xCaxMnO3 phase diagram and its temperature dependence is given. Clearly, distinct EFG behaviours for samples outside/inside the charge order (CO) region are observed. The…
Recent optical conductivity $\sigma(\omega)$ experiments have revealed an anomalous spectral distribution in the ferromagnetic phase of the perovskite system $La_{1-x}Sr_xMnO_3$. Using finite temperature diagonalization techniques we…
Spin-charge-orbital ordered structures in doped layered manganites are investigated using an orbital-degenerate double-exchange model tightly coupled to Jahn-Teller distortions. In the ferromagnetic phase, unexpected diagonal stripes at…
From a general model of the Mn oxides R_{1-x}A_{x}MnO_3, we derive an effective Hamiltonian in the low-energy subspace using the projection operator method, in which a novel coupling between the spin and orbital degrees of freedom is…
We report inelastic neutron scattering results on the spin dynamics in the 50 % hole-doped manganites, Pr{1/2}Sr{1/2}MnO3 and Nd{1/2}Sr{1/2}MnO3. In the paramagnetic phase, these systems exhibit a ridge-type diffuse scattering, indicating a…
We investigate a planar model for the ferromagnetic (FM) phase of manganites, which develops orbital order of $e_g$ electrons with x$^2$-y$^2$-symmetry at low temperature. The dynamic structure factor of orbital excitations and the optical…
Motivated by the recent ARPES measurements (Evtushinsky et. al., PRL {\bf 105}, 147201 (2010)) and evidence for the density-wave state for the charge and orbital ordering (Garc\'{i}a et al., PRL {\bf 109}, 107202 (2012)) in…
We summarize some characteristic features of the frustrated magnetic interactions in spin-orbital models adequate for cubic transition metal oxides with orbital degeneracy. A generic tendency towards dimerization, found already in the…
We consider a model of strongly correlated $e_g$ electrons interacting by superexchange orbital interactions in the ferromagnetic phase of LaMnO$_3$. It is found that the classical orbital order with alternating occupied $e_g$ orbitals has…
Spin-orbit coupling in magnetic systems lacking inversion symmetry can give rise to non trivial spin textures. Magnetic thin films and heterostructures are potential candidates for the formation of skyrmions and other non-collinear spin…
We investigate the highly frustrated spin and orbital superexchange interactions in cubic vanadates. The fluctuations of $t_{2g}$ orbitals trigger a {\it novel mechanism of ferromagnetic interactions} between spins S=1 of V$^{3+}$ ions…
The phase diagram of $Pr_{1-x}Ca_xMnO_3$ is modified x $\le$ 0.3, which suggests a reevaluation of the phase diagram of other manganites in that doping region. Rather than an orbital ordered phase reaching up to high temperatures of…
The high temperature paramagnetic state in an antiferromagnetic (AFM) insulator Pr_{1-x}Ca_{x}MnO_{3} is characterized by the ferromagnetic (FM) spin fluctuations with an anomalously small energy scale. The FM fluctuations show a…
We report resonant x-ray scattering studies of charge and orbital order in Pr_{1-x}Ca_{x}MnO_3 with x=0.4 and 0.5. Below the ordering temperature, T_O=245 K, the charge and orbital order intensities follow the same temperature dependence,…
We present a theory for spin excitations in ferromagnetic metallic manganites and demonstrate that orbital fluctuations have strong effects on the magnon dynamics in the case these compounds are close to a transition to an orbital ordered…
Magnetic and electronic structures in LaFeAsO in the single-stripe-type antiferromagnetic (AFM) phase are studied using first-principles density-functional calculations including the spin-orbit interaction. We show that the longitudinal…
Based on a two-dimensional extended Hubbard model with electron-phonon interaction, we have studied the effect of polaron formation on the charge ordering (CO) transition. It is found that for fully ferromagnetically ordered spins the CO…
The correlated motion of electrons in the presence of strong orbital fluctuations and correlations is investigated with respect to magnetic couplings and excitations in an orbitally degenerate ferromagnet. Introduction of the orbital degree…
Recent experiments showed that the robust charge-ordering in manganites can be weakened by reducing the grain size down to nanoscale. Weak ferromagnetism was evidenced in both nanoparticles and nanowires of charge-ordered manganites. To…
We study the effect of four-particle ring exchange process on orbital antiferromagnetic state that occurs in some correlated electron systems in two dimensions. The primary question is whether the ring exchange process enhances or…