First-principles study of complex ferromagnetic states in maghemite-related nanoparticles

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

First-principles study of complex ferromagnetic states in maghemite-related nanoparticles

Popis výsledku v původním jazyce

Maghemite γ-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 γ-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.

Název v anglickém jazyce

First-principles study of complex ferromagnetic states in maghemite-related nanoparticles

Popis výsledku anglicky

Maghemite γ-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 γ-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.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

10403 - Physical chemistry

Projekt

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Návaznosti

S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2024

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů