Two-, Three-, and Four-Component Magnetic Multilayer Onion Nanoparticles Based on Iron Oxides and Manganese Oxides

http://pubs.acs.org/doi/abs/10.1021/ja205810t
Journal of the American Chemical Society, 2011, 133, 16738–16741

German Salazar-Alvarez, Hans Lidbaum, Alberto López-Ortega, Marta Estrader, Klaus Leifer, Jordi Sort, Santiago Suriñach, Maria Dolors Baró, and Josep Nogués 

DOI: 10.1021/ja205810t

Magnetic multilayered, onion-like, heterostructured nanoparticles are interesting model systems for studying magnetic exchange coupling phenomena. In this work, we synthesized heterostructured magnetic nanoparticles composed of two, three, or four components using iron oxide seeds for the subsequent deposition of manganese oxide. The MnO layer was allowed either to passivate fully in air to form an outer layer of Mn₃O₄ or to oxidize partially to form MnO|Mn₃O₄ double layers. Through control of the degree of passivation of the seeds, particles with up to four different magnetic layers can be obtained (i.e., FeO|Fe₃O₄|MnO|Mn₃O₄). Magnetic characterization of the samples confirmed the presence of the different magnetic layers.