Effect of A -site cation ordering on the magnetoelectric properties in [ ( LaMnO 3 ) m / ( SrMnO 3 ) m ] n artificial superlattices

In order to evaluate the effect of charge transfer and/or charge ordering in ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ on the magnetic and transport properties, a library of $[({\mathrm{LaMnO}}_{3}{)}_{m}/({\mathrm{SrMnO}}_{3}{)}_{m}{]}_{n}$ superlattices have been fabricated by the combinatorial pulsed laser deposition method. The properties of superlattices were found to depend strongly on the periodicity m; superlattices of $ml~4$ behaved like a solid solution ${\mathrm{La}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3}$ film, while the superlattices of $mg4$ were significantly different from the solid solution. These superlattices exhibited a higher resistivity and lower Curie temperature than $ml~4$ superlattices. The results indicate that the properties of the superlattices are dominated not only by the magnetic interaction between the superlattice constituents but also by carrier ${(e}_{g}$ electrons) transfer thorough the superlattice interface. The contribution of carrier transfer is supported by the magnetoelectric properties of another library of $[({\mathrm{La}}_{0.8}{\mathrm{Sr}}_{0.2}{\mathrm{MnO}}_{3}{)}_{8}/({\mathrm{La}}_{0.2}{\mathrm{Sr}}_{0.8}{\mathrm{MnO}}_{3}{)}_{m}{]}_{12}$ superlattices. The A-site cation order can change both effective carrier concentration and magnetic interaction.