Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/102237
Title: Influence of dipolar interactions on the magnetic susceptibility spectra of ferrofluids
Authors: Sindt, J. O.
Camp, P. J.
Kantorovich, S. S.
Elfimova, E. A.
Ivanov, A. O.
Issue Date: 2016
Publisher: American Physical Society
Citation: Influence of dipolar interactions on the magnetic susceptibility spectra of ferrofluids / J. O. Sindt, P. J. Camp, S. S. Kantorovich, et al. — DOI 10.1103/PhysRevE.93.063117 // Physical Review E. — 2016. — Vol. 93. — Iss. 6. — 063117.
Abstract: 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. © 2016 American Physical Society.
Keywords: AUTOCORRELATION
MAGNETIC FLUIDS
MAGNETIC SUSCEPTIBILITY
AUTOCORRELATION FUNCTIONS
BROWNIAN DYNAMICS SIMULATIONS
DIPOLE DIPOLE INTERACTIONS
LOW FREQUENCY BEHAVIOR
PARTICLE POLYDISPERSITY
POLYDISPERSE FERROFLUIDS
QUANTITATIVE AGREEMENT
THEORETICAL FOUNDATIONS
POLYCRYSTALLINE MATERIALS
URI: http://hdl.handle.net/10995/102237
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 84977566069
PURE ID: 1027070
f3e67872-1b8b-44fa-8905-fa40487f1c68
ISSN: 24700045
DOI: 10.1103/PhysRevE.93.063117
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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