Reference : Dipolar-coupled moment correlations in clusters of magnetic nanoparticles

	Document type :	Scientific journals : Article
	Discipline(s) :	Physical, chemical, mathematical & earth Sciences : Physics
	Focus Areas :	Physics and Materials Science
	To cite this reference:	http://hdl.handle.net/10993/38322

Title :	Dipolar-coupled moment correlations in clusters of magnetic nanoparticles
Language :	English
Author, co-author :	Bender, Philipp Florian [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit >]
	Wetterskog, E. [> >]
	Honecker, Dirk [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit]
	Fock, J. [> >]
	Frandsen, C. [> >]
	Moerland, C. [> >]
	Bogart, L. K. [> >]
	Posth, O. [> >]
	Szczerba, W. [> >]
	Gavilán, H. [> >]
	Costo, R. [> >]
	Fernández-Díaz, M. T. [> >]
	González-Alonso, D. [> >]
	Fernández Barquín, L. [> >]
	Johansson, C. [> >]
Publication date :	2018
Journal title :	Physical Review. B, Condensed Matter
Publisher :	American Physical Society
Volume :	98
Pages :	224420
Peer reviewed :	Yes (verified by ORBilu)
Audience :	International
ISSN :	0163-1829
e-ISSN :	1095-3795
City :	New York
Country :	MD
Abstract :	[en] Here, we resolve the nature of the moment coupling between 10-nm dimercaptosuccinic acid–coated magnetic <br />nanoparticles. The individual iron oxide cores were composed of >95% maghemite and agglomerated to <br />clusters. At room temperature the ensemble behaved as a superparamagnet according to Mössbauer and magnetization <br />measurements, however, with clear signs of dipolar interactions. Analysis of temperature-dependent <br />ac susceptibility data in the superparamagnetic regime indicates a tendency for dipolar-coupled anticorrelations <br />of the core moments within the clusters. To resolve the directional correlations between the particle moments <br />we performed polarized small-angle neutron scattering and determined the magnetic spin-flip cross section <br />of the powder in low magnetic field at 300 K. We extract the underlying magnetic correlation function of <br />the magnetization vector field by an indirect Fourier transform of the cross section. The correlation function <br />suggests nonstochastic preferential alignment between neighboring moments despite thermal fluctuations, with <br />anticorrelations clearly dominating for next-nearest moments. These tendencies are confirmed by Monte Carlo <br />simulations of such core clusters.
Permalink :	http://hdl.handle.net/10993/38322
	also: http://hdl.handle.net/10993/38326 ; http://hdl.handle.net/10993/41165
DOI :	10.1103/PhysRevB.98.224420
Other URL :	https://journals.aps.org/prb/abstract/10.1103/PhysRevB.98.224420
Framework Programme / European Project :	FP7 ; 604448 - NANOMAG - Nanometrology Standardization Methods for Magnetic Nanoparticles

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