Orbital ordering in LaMnO3:: Electron-electron and electron-lattice interactions -: art. no. 144403

The interactions between e(g) orbitals in neighboring sites are investigated in LaMnO3 by taking into account virtual exchange of electrons and phonons. The spin and orbital ordering temperatures and the spin-wave dispersion relation are calculated. We find that the orbital ordering is mainly caused by the electronic interactions and that the Jahn-Teller coupling is much smaller than that reported previously. We propose that the elastic constant shows a characteristic change at the Neel temperature by the spin and orbital couplings and the higher-order Jahn-Teller coupling.