Signatures of enhanced ordering temperatures in digital superlattices of (LaMnO3)m/(SrMnO3)2m.

Digital superlattices of (LaMnO₃)_m/SrMnO₃)_2m (m≤3) having the same nominal composition as La_1/3Sr_2/3MnO₃, an antiferromagnetic insulator, have been synthesized by means of molecular beam epitaxy. All superlattices show a sharp resistive maximum at temperatures near to or higher than the Néel temperature of bulk La_1/3Sr_2/3MnO₃. No discernible signatures of magnetic ordering are observed near the resistivity peak for m≤2, but m=3 has a susceptibility peak consistent with antiferromagnet ordering, which is canted when cooled in a small magnetic field. Analogies are drawn to d_x²-y² orbitally ordered, layered antiferromagnetic manganites to explain the observations [ABSTRACT FROM AUTHOR]