Informace o publikaci
First-principles study of complex ferromagnetic states in maghemite-related nanoparticles
| Autoři | |
|---|---|
| Rok publikování | 2024 |
| Druh | Konferenční abstrakty |
| Fakulta / Pracoviště MU | |
| Citace | |
| Popis | Maghemite ?-Fe2O3 is a biocompatible ferrimagnetic mineral crystalizing in an inverse spinel lattice - it can be considered as magnetite Fe3O4 containing a high concentration of iron vacancies. The magnetic behavior of both maghemite and magnetite is similar except for the value of the magnetic moment. The magnetic moment of a magnetite is higher than that of a maghemite. In a nanoparticle form, maghemite has numerous applications, such asmagnetic resonance imaging agents, drug delivery, gas sensors, energy storage, bio-separation, purification, as well as many others profiting uses from the combination of its magnetic properties, biocompatibility and small size. As many experimental methods cannot distinguish magnetite and maghemite due to their structural similarity, we have employed quantum-mechanical calculations to study the local magnetic moments of individual atoms in maghemite-related nanoparticles. Motivated by results obtained for the bulk maghemite ?-Fe2O3, our calculations of nanoparticles started from the ferrimagnetic state when tetrahedrally and octahedrally O-coordinated Fe sublattices exhibit mutually opposite orientations of local magnetic moments. Importantly, our calculations indicate that the nanoparticle surfaces result in a much more complex magnetic state characterized by a „nested“ ferrimagnetism. It is characterized by local magnetic moments of Fe atoms with mutually opposite orientations appearing even within each of the two (tetrahedral or octahedral) sublattices. |