Anti-Jahn-Teller polaron in LaMnO3

Distortions of the oxygen sublattice couple to e(g) orbitals of Mn3+ and dr ive a cooperative Jahn-Teller (orbital ordering) transition in LaMnO3. A si mple model for this transition is studied. Without further adjustment, the model predicts the shape and stability of small (anti-Jahn-Teller) polarons that form when holes are doped into the material. This leads to a new desc ription of the lightly-doped insulator, the antiferromagnetic to ferromagne tic transition, and the metal-insulator transition. [S0163-1829(99)12639-0] .