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

Abstract

Digital superlattices of (LaMnO3)m∕(SrMnO3)2m (m⩽3) having the same nominal composition as La1∕3Sr2∕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 La1∕3Sr2∕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 dx2−y2 orbitally ordered, layered antiferromagnetic manganites to explain the observations.