Theoretical study of the dynamic magnetic response of ferrofluid to static and alternating magnetic fields

Batrudinov, Timur M.; Ambarov, Alexander V.; Elfimova, Ekaterina A.; Zverev, Vladimir S.; Иванов, А. П.

doi:10.1016/j.jmmm.2016.09.094

Cited by 10 publications

(7 citation statements)

References 15 publications

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“…As far as possible, the same notation will be used in each section to highlight the similarities between the derivations, but the details will be different. In each case, results for non-interacting systems will be outlined first [34], and then the effects of interactions will be described.…”

Section: A Model and Basic Propertiesmentioning

confidence: 99%

“…Combining Eqs. (34) and (45) and linearizing with respect to the small parameter α leads to the solution…”

Section: Interacting Particlesmentioning

confidence: 99%

“…The aim of the current work is to fill that gap using the modified mean-field approach, and to test the predictions against numerical results from BD simulations. An outline of the theoretical framework for non-interacting systems has already been published [34], and this paves the way for including interactions.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic magnetic response of a ferrofluid in a static uniform magnetic field

et al. 2018

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Dynamic magnetic response of a ferrofluid in a static uniform magnetic fieldCitation for published version: Batrudinov, TM, Nekhoroshkova, YE, Paramonov, EI, Zverev, VS, Elfimova, EA, Ivanov, AO & Camp, PJ 2018, 'Dynamic magnetic response of a ferrofluid in a static uniform magnetic field', Physical Review E, vol. 98, no. 5. https://doi. AbstractA theory for the frequency-dependent magnetic susceptibility of a ferrofluid in a static uniform magnetic field is developed, including the dipolar interactions between the constituent particles.Interactions are included within the framework of modified mean-field theory. Predictions are given for the linear responses of the magnetization to a probing ac field both parallel and perpendicular to the static field, and are tested against results from Brownian dynamics simulations. The effects of particle concentration and dipolar coupling constant on the field-dependent static susceptibilities and the frequency dispersions are shown to be substantial, which justifies taking proper account of the interactions between particles. The theory is reliable provided that the volume concentration and dipolar coupling constant are not too large, and within the range of values for real ferrofluids.

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Section: A Model and Basic Propertiesmentioning

confidence: 99%

“…Combining Eqs. (34) and (45) and linearizing with respect to the small parameter α leads to the solution…”

Section: Interacting Particlesmentioning

confidence: 99%

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Dynamic magnetic response of a ferrofluid in a static uniform magnetic field

et al. 2018

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“…The dynamics of magnetic relaxation have been the subject of several experimental [28][29][30][31][32][33][34][35][36][37] and simulation [38][39][40][41][42][43][44][45][46] studies. Theoretically, the influence of the interactions on the so-called dynamic (or frequency-dependent) initial magnetic susceptibility has been evaluated within various approaches [41,42,[47][48][49][50][51][52][53][54]. Predictions from modified mean-field approaches (described below) have been tested critically against experimental [35,36] and simulation results [40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Effects of interactions on magnetization relaxation dynamics in ferrofluids

Иванов

Camp

2020

Phys. Rev. E

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The dynamics of magnetization relaxation in ferrofluids are studied with statistical-mechanical theory and Brownian dynamics simulations. The particle dipole moments are initially perfectly aligned, and the magnetization is equal to its saturation value. The magnetization is then allowed to decay under zero-field conditions toward its equilibrium value of zero. The time dependence is predicted by solving the Fokker-Planck equation for the one-particle orientational distribution function. Interactions between particles are included by introducing an effective magnetic field acting on a given particle and arising from all of the other particles. Two different approximations are proposed and tested against simulations: a first-order modified mean-field theory and a modified Weiss model. The theory predicts that the short-time decay is characterized by the Brownian rotation time τ B , independent of the interaction strength. At times much longer than τ B , the asymptotic decay time is predicted to grow with increasing interaction strength. These predictions are borne out by the simulations. The modified Weiss model gives the best agreement with simulation, and its range of validity is limited to moderate, but realistic, values of the dipolar coupling constant.

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“…The main characteristic that describes the dynamic magnetic response of a ferrofluid to an AC field is the dynamic susceptibility. Most of the known theoretical models of the dynamic magnetic response of ferrofluids concern noninteracting samples [13][14][15][16][17][18][19][20][21]. For example, the dynamic susceptibility of a ferrofluid in a weak AC magnetic field is described by the well-known Debye formula [15,16].…”

Section: Introductionmentioning

confidence: 99%

Computer Simulations of Dynamic Response of Ferrofluids on an Alternating Magnetic Field with High Amplitude

et al. 2021

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The response of ferrofluids to a high-amplitude AC magnetic field is important for several applications including magnetic hyperthermia and biodetection. In computer simulations of the dynamic susceptibility of a ferrofluid outside the linear response region, there are several problems associated with the fact that an increase in the frequency of the AC field leads to the appearance of additional computational errors, which can even lead to unphysical results. In this article, we study the dependence of the computational error arising in the computer simulation of the dynamic susceptibility on the input parameters of the numerical algorithm: the length of the time step, the total number of computer simulation periods, and averaging period. Computer simulation is carried out using the Langevin dynamics method and takes Brownian rotational relaxation of magnetic particles and interparticle interactions into account. The reference theory [Yoshida T.; Enpuku K. Jap. J. Ap. Phys. 2009] is used to estimate computational error. As a result, we give practical recommendations for choosing the optimal input parameters of the numerical algorithm, which make it possible to obtain reliable results of the dynamic susceptibility of a ferrofluid in a high-amplitude AC field in a wide frequency range.

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Theoretical study of the dynamic magnetic response of ferrofluid to static and alternating magnetic fields

Cited by 10 publications

References 15 publications

Dynamic magnetic response of a ferrofluid in a static uniform magnetic field

Dynamic magnetic response of a ferrofluid in a static uniform magnetic field

Effects of interactions on magnetization relaxation dynamics in ferrofluids

Computer Simulations of Dynamic Response of Ferrofluids on an Alternating Magnetic Field with High Amplitude

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