Effect of A-site cation ordering on the magnetoelectric properties in [(LaMnO₃)_m/(SrMnO₃)_m]_n artificial superlattices

In order to evaluate the effect of charge transfer and/or charge ordering in La_1-xSr_xMnO₃ on the magnetic and transport properties, a library of [(LaMnO₃)_m/(SrMnO₃)_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 m<~4 behaved like a solid solution La_0.5Sr_0.5MnO₃ film, while the superlattices of m>4 were significantly different from the solid solution. These superlattices exhibited a higher resistivity and lower Curie temperature than m<~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 [(La_0.8Sr_0.2MnO₃)₈/(La_0.2Sr_0.8MnO₃)_m]₁₂ superlattices. The A-site cation order can change both effective carrier concentration and magnetic interaction.