Neutron scattering studies of magnetic order in complex oxide superlattices

Steve May, Argonne National Lab

The synthesis of complex oxide superlattices with single unit cell control and abrupt interfaces has opened two new routes to stabilizing unusual or enhanced magnetic properties in materials. First, magnetic behavior confined to interfaces can arise from the different spin, charge, or orbital ground states of the adjoined compounds. However, definitive measurements of interfacial phenomena are challenging due to the difficulty of directly measuring behavior at buried interfaces. I will discuss recent polarized neutron reflectivity results, in which we obtained quantitative measurements of interfacial ferromagnetism in a superlattice consisting of two nominal antiferromagnets, (LaMnO3)/(SrMnO3). Second, chemically ordered analogues of complex oxides can be synthesized in order to enhance magnetic ordering that remains coherent through an entire sample. I will discuss our studies of the effect of cation-site disorder in antiferromagnetic (AF) manganite superlattices. Using neutron diffraction, we have confirmed a 60 K enhancement of the Néel temperature in (LaMnO3)1/(SrMnO3)2 superlattices compared to the La1/3Sr2/3MnO3 random alloys.

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