Orbital excitations in LaMnO3

Abstract

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 mixed modes with both orbital and phonon character. It is proposed that the satellite structures observed in recent Raman-scattering experiments on LaMnO3 are actually orbiton derived satellites in the phonon spectral function, caused by the phonon-orbiton interaction. © 2001 The American Physical Society.