Influence of dipolar interactions on the magnetic susceptibility spectra of ferrofluids
| Autor: | Sofia S. Kantorovich, Ekaterina A. Elfimova, Julien O. Sindt, Alexey O. Ivanov, Philip J. Camp |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Ferrofluid
02 engineering and technology 01 natural sciences AUTOCORRELATION DIPOLE DIPOLE INTERACTIONS POLYDISPERSE FERROFLUIDS Spectral line Magnetization 0103 physical sciences BROWNIAN DYNAMICS SIMULATIONS Soft matter QUANTITATIVE AGREEMENT 010306 general physics Physics Condensed matter physics LOW FREQUENCY BEHAVIOR PARTICLE POLYDISPERSITY MAGNETIC FLUIDS 021001 nanoscience & nanotechnology Magnetic susceptibility Dipole AUTOCORRELATION FUNCTIONS POLYCRYSTALLINE MATERIALS Particle MAGNETIC SUSCEPTIBILITY 0210 nano-technology THEORETICAL FOUNDATIONS Magnetic dipole–dipole interaction |
| Zdroj: | Sindt, J O, Camp, P J, Kantorovich, S S, Elfimova, E A & Ivanov, A O 2016, ' Influence of dipolar interactions on the magnetic susceptibility spectra of ferrofluids ', Physical Review E, vol. 93, no. 6, 063117 . https://doi.org/10.1103/PhysRevE.93.063117 Phys. Rev. E Physical Review E |
| ISSN: | 1744-683X |
| DOI: | 10.1103/PhysRevE.93.063117 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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