Role of electron-lattice interactions in determining the magnetic structure of insulating manganites

Together with the strong electron-electron interactions, the role of the la ttice distorsions turns out to be relevant in determining the specific magn etic structure of some insulating manganites. In particular, while a substa ntial Jahn-Teller distorsion is needed to account for the layered antiferro magnetic structure of LaMnO3, the observed collective shear of alternate io ns in La0.5Ca0.5MnO3 is required to stabilize the CE magnetic structure of this compounds. The specific action of the lattice in stabilizing these pec uliar magnetic orderings is thus clarified.