Orbiton-phonon coupling in the localized limit

In systems with orbital order there is an elementary excitation, orbiton, due to the breaking of orbital symmetry. It is shown that there is both a correlation and dynamical lattice contribution to the orbital excitation, which makes the orbiton an intrinsically mixed mode. A localized model calculation shows that in the phonon excitation spectrum weak satellites appear at the orbiton energy, in qualitative agreement with Raman experiments on LaMnO3.