Control of the orbital ordering in manganite superlattices and impact on properties
Résumé
The present paper theoretically studies the possibility to control the orbital ordering in manganite superlattices. Indeed, favored d z 2 e g-orbital occupancy is one of the proposed interpretations for the formation of a "dead" layer at the interfaces in manganite thin films and superlattices. We show here that favored d z 2 e g-orbital occupancy at the interfaces can be prevented by using alkaline-earth simple oxides as alternating layers in very thin superlattices. Such an alternating layer promotes the contraction of the manganite layers at the interfaces and favors a d x 2 −y 2 e g orbital occupancy. This result holds for different manganites, different alkaline-earth simple oxides, as well as different thicknesses of the two layers. While Boltzmann's transport calculations on different superlattices show unexpectedly only weak dependence of the electrical conductivity on the orbital ordering, the enhanced occupation of the d x 2 −y 2 orbital should result in an increased Curie temperature.