title: Orbital ordering in LaMnO3 : electron-electron versus electron-lattice interactions.
abstract: The relative importance of electron-lattice (e-l) and electron-electron (e-e) interactions in ordering orbitals in LaMnO3 is systematically examined within the local-density approximation + Hubbard U approximation of density functional theory. A realistic effective Hamiltonian is derived from novel Wannier state analysis of the electronic structure. Surprisingly, e-l interaction (approximately or = 0.9 eV) alone is found insufficient to stabilize the orbital ordered state. On the other hand, e-e interaction (approximately or = 1.7 eV) not only induces orbital ordering, but also greatly facilitates the Jahn-Teller distortion via enhanced localization. Further experimental means to quantify the competition between these two mechanisms are proposed.
authors.affiliation: Physics Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Yin
authors.forename: Dmitri
authors.initials: D
authors.lastname: Volja
authors.forename: Wei
authors.initials: W
authors.lastname: Ku