Reference : Dipolar-coupled moment correlations in clusters of magnetic nanoparticles
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Physics
Physics and Materials Science
http://hdl.handle.net/10993/41165
Dipolar-coupled moment correlations in clusters of magnetic nanoparticles
English
Bender, Philipp Florian mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit]
Wetterskog, Erik [> >]
Honecker, Dirk mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit]
Fock, Jeppe [> >]
Frandsen, Cathrine [> >]
Moerland, Christian [> >]
Bogart, Lara K. [> >]
Posth, Oliver [> >]
Szczerba, Wojciech [> >]
Gavilán, Helena [> >]
others [> >]
2018
Physical Review B
American Physical Society
98
22
224420
Yes
International
[en] Here, we resolve the nature of the moment coupling between 10-nm dimercaptosuccinic acid–coated magnetic
nanoparticles. The individual iron oxide cores were composed of >95% maghemite and agglomerated to
clusters. At room temperature the ensemble behaved as a superparamagnet according to Mössbauer and magnetization
measurements, however, with clear signs of dipolar interactions. Analysis of temperature-dependent
ac susceptibility data in the superparamagnetic regime indicates a tendency for dipolar-coupled anticorrelations
of the core moments within the clusters. To resolve the directional correlations between the particle moments
we performed polarized small-angle neutron scattering and determined the magnetic spin-flip cross section
of the powder in low magnetic field at 300 K. We extract the underlying magnetic correlation function of
the magnetization vector field by an indirect Fourier transform of the cross section. The correlation function
suggests nonstochastic preferential alignment between neighboring moments despite thermal fluctuations, with
anticorrelations clearly dominating for next-nearest moments. These tendencies are confirmed by Monte Carlo
simulations of such core clusters.
http://hdl.handle.net/10993/41165

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