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Origin of reduced magnetization and domain formation in small magnetite nanoparticles

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ABSTRACT

The structural, chemical, and magnetic properties of magnetite nanoparticles are compared. Aberration corrected scanning transmission electron microscopy reveals the prevalence of antiphase boundaries in nanoparticles that have significantly reduced magnetization, relative to the bulk. Atomistic magnetic modelling of nanoparticles with and without these defects reveals the origin of the reduced moment. Strong antiferromagnetic interactions across antiphase boundaries support multiple magnetic domains even in particles as small as 12–14 nm.

No MeSH data available.


Conventional TEM images of (a) Sun, (b) Colvin, (c) Hyeon nanoparticles. Zero Field Cooled (ZFC) and Field Cooled (FC) magnetization curves for (d) Sun, (e) Colvin, (f) Hyeon nanoparticles.
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f1: Conventional TEM images of (a) Sun, (b) Colvin, (c) Hyeon nanoparticles. Zero Field Cooled (ZFC) and Field Cooled (FC) magnetization curves for (d) Sun, (e) Colvin, (f) Hyeon nanoparticles.

Mentions: The experiments compared 12–14 nm diameter iron oxide nanoparticles synthesized by three well-established methods that were pioneered by the groups of Sun17, Colvin18 and Hyeon19. Hereafter, they will be referred to as Sun, Colvin and Hyeon NPs. All three synthesis methods involve high temperature inert atmosphere decomposition in organic solvents, leading to monodisperse, highly crystalline, spherical particles coated with surfactants. Large field of view electron microscopy images for all three sets of NPs are presented in Fig. 1a–c and Supplementary Fig. S1. The size distribution of the three samples is similar: Sun 12.3 ± 2.9 nm, Colvin 13.7 ± 1.6 nm and Hyeon 14.2 ± 2.0 nm.


Origin of reduced magnetization and domain formation in small magnetite nanoparticles
Conventional TEM images of (a) Sun, (b) Colvin, (c) Hyeon nanoparticles. Zero Field Cooled (ZFC) and Field Cooled (FC) magnetization curves for (d) Sun, (e) Colvin, (f) Hyeon nanoparticles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5385549&req=5

f1: Conventional TEM images of (a) Sun, (b) Colvin, (c) Hyeon nanoparticles. Zero Field Cooled (ZFC) and Field Cooled (FC) magnetization curves for (d) Sun, (e) Colvin, (f) Hyeon nanoparticles.
Mentions: The experiments compared 12–14 nm diameter iron oxide nanoparticles synthesized by three well-established methods that were pioneered by the groups of Sun17, Colvin18 and Hyeon19. Hereafter, they will be referred to as Sun, Colvin and Hyeon NPs. All three synthesis methods involve high temperature inert atmosphere decomposition in organic solvents, leading to monodisperse, highly crystalline, spherical particles coated with surfactants. Large field of view electron microscopy images for all three sets of NPs are presented in Fig. 1a–c and Supplementary Fig. S1. The size distribution of the three samples is similar: Sun 12.3 ± 2.9 nm, Colvin 13.7 ± 1.6 nm and Hyeon 14.2 ± 2.0 nm.

View Article: PubMed Central - PubMed

ABSTRACT

The structural, chemical, and magnetic properties of magnetite nanoparticles are compared. Aberration corrected scanning transmission electron microscopy reveals the prevalence of antiphase boundaries in nanoparticles that have significantly reduced magnetization, relative to the bulk. Atomistic magnetic modelling of nanoparticles with and without these defects reveals the origin of the reduced moment. Strong antiferromagnetic interactions across antiphase boundaries support multiple magnetic domains even in particles as small as 12–14 nm.

No MeSH data available.