Die u:cris Detailansicht:

Influence of dipolar interactions on the magnetic susceptibility spectra of ferrofluids

Autor(en)
Julien O. Sindt, Philip J. Camp, Sofia S. Kantorovich, Ekaterina A. Elfimova, Alexey O. Ivanov
Abstrakt

The frequency-dependent magnetic susceptibility of a ferrofluid is calculated under the assumption that the constituent particles undergo Brownian relaxation only. Brownian-dynamics simulations are carried out in order to test the predictions of a recent theory [A. O. Ivanov, V. S. Zverev, and S. S. Kantorovich, Soft Matter 12, 3507 (2016)1744-683X10.1039/C5SM02679B] that includes the effects of interparticle dipole-dipole interactions. The theory is based on the so-called modified mean-field approach and possesses the following important characteristics: in the low-concentration, noninteracting regime, it gives the correct single-particle Debye-theory results; it yields the exact leading-order results in the zero-frequency limit; it includes particle polydispersity correctly from the outset; and it is based on firm theoretical foundations allowing, in principle, systematic extensions to treat stronger interactions and/or higher concentrations. The theory and simulations are compared in the case of a model monodisperse ferrofluid, where the effects of interactions are predicted to be more pronounced than in a polydisperse ferrofluid. The susceptibility spectra are analyzed in detail in terms of the low-frequency behavior, the position of the peak in the imaginary (out-of-phase) part, and the characteristic decay time of the magnetization autocorrelation function. It is demonstrated that the theory correctly predicts the trends in all of these properties with increasing concentration and dipolar coupling constant, the product of which is proportional to the Langevin susceptibility χL. The theory is in quantitative agreement with the simulation results as long as χL1.

Organisation(en)
Computergestützte Physik und Physik der Weichen Materie
Externe Organisation(en)
University of Edinburgh, Ural Federal University
Journal
Physical Review E
Band
93
Anzahl der Seiten
11
ISSN
1539-3755
DOI
https://doi.org/10.1103/PhysRevE.93.063117
Publikationsdatum
06-2016
Peer-reviewed
Ja
ÖFOS 2012
103015 Kondensierte Materie, 103006 Chemische Physik
Schlagwörter
ASJC Scopus Sachgebiete
Condensed Matter Physics, Statistical and Nonlinear Physics, Statistics and Probability
Link zum Portal
https://ucrisportal.univie.ac.at/de/publications/6a8aeed2-aff4-4719-a230-8dbfa4fef776