Origin of the charge-ordered stripe with the orbital ordering in manganese oxides

The origin of the charge-ordered stripe with the orbital ordering observed experimentally in some manganese oxides is proposed. It is emphasized that the long-range Coulomb interaction plays an essential role. We study a Hubbard model with doubly degenerate orbitals, and treat the on-site Coulomb interaction (U) and the nearest-neighbor one (V) with the Hartree-Fock approximation. Charge-orbital stripe structures observed in experiments are reproduced in a wide region of the U-V phase diagram. The stability of the stripe structure is confirmed by perturbation theory. (C) 2000 Elsevier Science B.V. All rights reserved.