The Composition and Magnetic Structure of Fe3O4/γ-Fe2O3 Core-Shell Nanocomposites under External Magnetic Field: Mössbauer Study (Part II)

The composition and the magnetic structure of Fe3O4/γ-Fe2O3 nanoparticles placed into external magnetic field with a strength of 1.8 kOe are studied with Mössbauer spectroscopy. We showed that the thickness of the maghemite (γ-Fe2O3) shell can be changed by the synthesis conditions. We found that there is a layer, in which the magnetic moments are not oriented collinearly to those located in the depth of the shell, on the surface of maghemite (γ-Fe2O3) shell in the Fe3O4/γ-Fe2O3 nanocomposites; in other words, there is a canted spin structure. An intermediate layer in the spin-glass state is formed between the core and the shell. The data on structure of core/shell particles are important to understand the properties of nanocomposites, which are of great interest to apply in various fields, including biomedicine.