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With the goal of observing and explaining the unexpected exchange bias effect in paramagnetic LaNiO 3 -based superlattices, a wide range of theoretical and experimental research has been published. Within the scope of this work, we have grown high-quality epitaxial LaMnO 3 (n)-LaNiO 3 (n) (LMO/LNO) superlattices (SLs) along (001)-, (110)-, and (111)-oriented SrTiO 3 substrates. The exchange bias effect is observed in all cases, regardless of growth orientation of the LMO/LNO SLs. As a result of a combination of a number of synchrotron based x-ray spectroscopy measurements, this effect is attributed to the interfacial charge transfer from Mn to Ni ions that induces localized magnetic moments to pin the ferromagnetic LMO layer. The interaction per area between interfacial Mn and Ni ions is nearly consistent and has no effect on charge transfer for different orientations. The discrepant charge transfer and orbital occupancy can be responsible for the different magnetic properties in LMO/LNO superlattices. Our experimental results present a promising advancement in understanding the origin of magnetic properties along different directions in these materials.

Corn-like, γ-Fe 2 O 3 @SiO 2 @TiO 2 core/shell heterostructures were synthesized by a modified solvothermal reduction combined with a sol-gel method. SiO 2 shells were first deposited on monodisperse Fe 3 O 4 microspheres by a sol-gel method. Fe 3 O 4 @SiO 2 @TiO 2 corn-like heterostructures were then obtained by sequential TiO 2 coating, during which the magnetic dipolar interactions induced the anisotropic self-assembly process. After annealing at 350 °C, the crystalized TiO 2 enhanced photocatalytic activity, while Fe 3 O 4 was converted to γ-Fe 2 O 3 . The corn-like γ-Fe 2 O 3 @SiO 2 @TiO 2 photocatalyst can be recycled and reused by magnet extraction. Despite the photocatalytic activity decreased with each cycle, it can be completely recovered by moderate heating at 200 °C.