Electronic and magnetic structure of the (LaMnO3)2n/(SrMnO3)n superlattices

We study the magnetic structure of the (LaMnO3)2n/(SrMnO3)n superlattices from density-functional calculations. In agreement with the experiments, we find that the magnetism changes with the layer thickness n. The reason for the different magnetic structures is shown to be the varying potential barrier across the interface, which controls the leakage of the Mn-eg electrons from the LaMnO3 side to the SrMnO3 side. This in turn affects the interfacial magnetism via the carrier-mediated Zener double exchange. For the n=1 superlattice, the Mn-eg electrons are more or less spread over the entire lattice so that the magnetic behavior is similar to the equivalent alloy compound La2/3Sr1/3MnO3. For larger n, the eg electron transfer occurs mostly between the two layers adjacent to the interface, thus leaving the magnetism unchanged and bulklike away from the interface region.This work was supported by the U.S. Department of Energy under Grant No. DE-FG02-00ER45818. We thank J. W. Freeland for stimulating this work and for valuable discussions