Evolution of orbital phases with particle size in nanoscale stoichiometric LaMnO3

Orbital Excitations in LaMnO3

We study the recently observed orbital excitations, orbitons, and treat electron-electron correlations and lattice dynamics on an equal footing. It is shown that the orbiton energy and dispersion are determined by both correlations and lattice vibrations. The electron-phonon coupling causes satellite structures in the orbiton spectral function and the elementary excitations of the system are mi...

Orbital correlations in the pseudocubic O and rhombohedral R phases of LaMnO3.

The local and intermediate structure of stoichiometric LaMnO3 has been studied in the pseudocubic and rhombohedral phases at high temperatures (300-1150 K). Neutron powder diffraction data were collected and a combined Rietveld and high real space resolution atomic pair distribution function analysis was carried out. The nature of the Jahn-Teller (JT) transition around 750 K is confirmed to be ...

Dynamic Evolution of Droplet/Particle Size Distribution in Suspension Polymerization of Styrene

Orbital ordering in paramagnetic LaMnO3 and KCuF3

Ab initio studies of the stability of orbital ordering, its coupling to magnetic structure and its possible origins ~electron-phonon and/or electron-electron interactions! are reported for two perovskite systems, LaMnO3 and KCuF3. We present an average spin state calculational scheme that allowed us to treat a paramagnetic state and to succesfully describe the experimental magnetic or orbital p...

Origin of Jahn-Teller distortion and orbital order in LaMnO3.

The origin of the cooperative Jahn-Teller distortion and orbital order in LaMnO3 is central to the physics of the manganites. The question is complicated by the simultaneous presence of tetragonal and GdFeO3-type distortions and the strong Hund's rule coupling between e{g} and t{2g} electrons. To clarify the situation we calculate the transition temperature for the Kugel-Khomskii superexchange ...