Absence of Hole Confinement in Transition Metal Oxides with Orbital   Degeneracy
  We investigate the spectral properties of a hole moving in a two-dimensional Hubbard model for strongly correlated t_2g electrons. Although superexchange interactions are Ising-like, a quasi-one-dimensional coherent hole motion arises due to effective three-site terms. This mechanism is fundamentally different from the hole motion via quantum fluctuations in the conventional spin model with SU(2) symmetry. The orbital model describes also propagation of a hole in some e_g compounds, and we argue that orbital degeneracy alone does not lead to hole self-localization. 
M. Daghofer, K. Wohlfeld, A. M. Oles, E. Arrigoni, P. Horsch