Interplay between inter- and intraparticle interactions in bi-magnetic core/shell nanoparticles

Omelyanchik, Alexander; Villa, Silvia; Vasilakaki, Marianna; Singh, Gurvinder; Ferretti, Anna M.; Ponti, Alessandro; Canepa, F.; Margaris, G.; Trohidou, K. N.; Peddis, Davide

doi:10.1039/d1na00312g

Cited by 15 publications

(13 citation statements)

References 70 publications

(121 reference statements)

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“…Recently, a similar experimental observation, confirmed also by Monte Carlo simulations, has been explained with the coupling between a magnetically disordered surface shell and an ordered core, responsible for an additional negative contribution to ΔM plots [65]. A similar effect has been also observed in bi-magnetic exchange-coupled systems [68]. Noteworthy, the comparison of interparticle interactions in the set of samples under investigation requires special care, due to the different average magnetic anisotropy in each sample.…”

Section: Interparticle Interactionssupporting

confidence: 62%

The Boundary Between Volume and Surface-Driven Magnetic Properties in Spinel Iron Oxide Nanoparticles

et al. 2022

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Despite modern preparation techniques offer the opportunity to tailor the composition, size, and shape of magnetic nanoparticles, understanding and hence controlling the magnetic properties of such entities remains a challenging task, due to the complex interplay between the volume-related properties and the phenomena occurring at the particle’s surface. The present work investigates spinel iron oxide nanoparticles as a model system to quantitatively analyze the crossover between the bulk and the surface-dominated magnetic regimes. The magnetic properties of ensembles of nanoparticles with an average size in the range of 5–13 nm are compared. The role of surface anisotropy and the effect of oleic acid, one of the most common and versatile organic coatings, are discussed. The structural and morphological properties are investigated by X-ray diffraction and transmission electron microscopy. The size dependence of the surface contribution to the effective particle anisotropy and the magnetic structure are analyzed by magnetization measurements and in-field Mössbauer spectrometry. The structural data combined with magnetometry and Mössbauer spectrometry analysis are used to shed light on this complex scenario revealing a crossover between volume and surface-driven properties in the range of 5–7 nm. Graphical Abstract

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Section: Interparticle Interactionssupporting

confidence: 62%

The Boundary Between Volume and Surface-Driven Magnetic Properties in Spinel Iron Oxide Nanoparticles

et al. 2022

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“…The single-phase core system was synthesized following a modified procedure reported elsewhere [17,18]. To synthesize the CoFe 2 O 4 core, (CFO sample), Fe(acac) 3 (2 mmol), Co(acac) 2 (1 mmol), 1,2-hexadecanediol (10 mmol), OA (6 mmol), OLA (6 mmol), and benzyl ether (20 mL) were mixed and magnetically stirred under a flow of nitrogen.…”

Section: Synthesis Of Npsmentioning

confidence: 99%

Magnetic Properties of Bi-Magnetic Core/Shell Nanoparticles: The Case of Thin Shells

et al. 2021

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Bi-magnetic core/shell nanoparticles were synthesized by a two-step high-temperature decomposition method of metal acetylacetonate salts. Transmission electron microscopy confirmed the formation of an ultrathin shell (~0.6 nm) of NiO and NiFe2O4 around the magnetically hard 8 nm CoFe2O4 core nanoparticle. Magnetization measurements showed an increase in the coercivity of the single-phase CoFe2O4 seed nanoparticles from ~1.2 T to ~1.5 T and to ~2.0 T for CoFe2O4/NiFe2O4 and CoFe2O4/NiO, respectively. The NiFe2O4 shell also increases the magnetic volume of particles and the dipolar interparticle interactions. In contrast, the NiO shell prevents such interactions and keeps the magnetic volume almost unchanged.

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“…During the last decades magnetic nanostructured materials composed of two or more magnetic phases (e.g., composite nanoparticle assemblies, nanoparticles in matrices or core/shell nanoparticles) have been extensively studied both from fundamental and applied viewpoints. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] From a basic science perspective, issues like dipolar and exchange interactions, collective behavior, magnetic graded interfaces, proximity effects, among many others, have been investigated. Additionally, bi-magnetic materials are being studied for countless applications, like biomedical uses (e.g., magnetic hyperthermia and magnetic resonance imaging), permanent magnets, magnetic recording, magnetic refrigeration, or microwave absorption.…”

Section: Introductionmentioning

confidence: 99%

Elucidating Individual Magnetic Contributions in Bi‐Magnetic Fe₃O₄/Mn₃O₄ Core/Shell Nanoparticles by Polarized Powder Neutron Diffraction

et al. 2023

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Heterogeneous bi‐magnetic nanostructured systems have had a sustained interest during the last decades owing to their unique magnetic properties and the wide range of derived potential applications. However, elucidating the details of their magnetic properties can be rather complex. Here, a comprehensive study of Fe3O4/Mn3O4 core/shell nanoparticles using polarized neutron powder diffraction, which allows disentangling the magnetic contributions of each of the components, is presented. The results show that while at low fields the Fe3O4 and Mn3O4 magnetic moments averaged over the unit cell are antiferromagnetically coupled, at high fields, they orient parallel to each other. This magnetic reorientation of the Mn3O4 shell moments is associated with a gradual evolution with the applied field of the local magnetic susceptibility from anisotropic to isotropic. Additionally, the magnetic coherence length of the Fe3O4 cores shows some unusual field dependence due to the competition between the antiferromagnetic interface interaction and the Zeeman energies. The results demonstrate the great potential of the quantitative analysis of polarized neutron powder diffraction for the study of complex multiphase magnetic materials.

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Interplay between inter- and intraparticle interactions in bi-magnetic core/shell nanoparticles

Abstract: The synthesis strategy and magnetic characterisation of two systems consisting of nanoparticles with core/shell morphology are presented: an assembly of hard/soft nanoparticles with cores consisting of magnetically hard cobalt ferrite...

Cited by 15 publications

References 70 publications

The Boundary Between Volume and Surface-Driven Magnetic Properties in Spinel Iron Oxide Nanoparticles

The Boundary Between Volume and Surface-Driven Magnetic Properties in Spinel Iron Oxide Nanoparticles

Magnetic Properties of Bi-Magnetic Core/Shell Nanoparticles: The Case of Thin Shells

Elucidating Individual Magnetic Contributions in Bi‐Magnetic Fe₃O₄/Mn₃O₄ Core/Shell Nanoparticles by Polarized Powder Neutron Diffraction

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Interplay between inter- and intraparticle interactions in bi-magnetic core/shell nanoparticles

Abstract: The synthesis strategy and magnetic characterisation of two systems consisting of nanoparticles with core/shell morphology are presented: an assembly of hard/soft nanoparticles with cores consisting of magnetically hard cobalt ferrite...

Cited by 15 publications

References 70 publications

The Boundary Between Volume and Surface-Driven Magnetic Properties in Spinel Iron Oxide Nanoparticles

The Boundary Between Volume and Surface-Driven Magnetic Properties in Spinel Iron Oxide Nanoparticles

Magnetic Properties of Bi-Magnetic Core/Shell Nanoparticles: The Case of Thin Shells

Elucidating Individual Magnetic Contributions in Bi‐Magnetic Fe3O4/Mn3O4 Core/Shell Nanoparticles by Polarized Powder Neutron Diffraction

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Elucidating Individual Magnetic Contributions in Bi‐Magnetic Fe₃O₄/Mn₃O₄ Core/Shell Nanoparticles by Polarized Powder Neutron Diffraction