Interparticle magnetic correlations in dense Co nanoparticle assemblies Page: 2 of 15
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
Magnetic nanoparticles with a protective organic shell self-assemble into densely
packed arrays [1, 2]. Close interparticle spacing in dense arrays increases the dipolar
interaction energy to compete with single-particle anisotropy, Zeeman, and thermal
energies [3, 4]. Macroscopic magnetic measurements [5, 6, 7, 8, 9, 10] and
micromagnetic modeling studies [3, 4, 11, 12] suggest the importance of dipolar
interactions, that are thought to lead to collective behavior below the blocking
temperature of otherwise superparamagnetic particles [3, 11, 6]. Few measurements,
however, are sensitive to interactions at interparticle length scales where dipolar fields
should be most pronounced.
The magnetostatic energy between dipoles p, and p, separated by r, ,
E D =(p, - pj)/rt - 3(p, - r, )(p, - rj )/r , has minima ranging from ferromagnetic (F)
alignment when p, , p, and t, are collinear, to antiferromagnetic (AF) alignment when
collinear p, and p, are orthogonal to r, . Orientations taken by interacting dipoles in
dense 3-D samples are thus not simple, often involving frustration and spin-glass
behavior. The correlation function = (p, p,) is a useful descriptor for the ensemble of
local dipole-dipole correlations, since it has positive and negative extrema for these same
collinear F and transverse AF order, respectively [3].
In this letter we study dense, self-assembled systems of 9 nm superparamagnetic
Co particles using resonant magnetic x-ray scattering at wavelengths short enough to
resolve nearest neighbor structure and provide sensitivity to . Combining applied fields
and variable incident polarization we confirm theoretical predictions of charge-charge,
magnetic-magnetic, and charge-magnetic contributions to this scattering. Pure magnetic2
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Kortright, Jeffrey B.; Hellwig, Olav; Sun, Shouheng & Fullerton, Eric E. Interparticle magnetic correlations in dense Co nanoparticle assemblies, article, January 16, 2004; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc786919/m1/2/: accessed March 29, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.