Magnetic properties of polydisperse ferrofluids: A critical comparison between experiment, theory, and computer simulation

Иванов, А. П.; Kantorovich, Sofia S.; Reznikov, Evgeniy N.; Holm, Christian; Pshenichnikov, A. F.; Lebedev, A. V.; Chremos, Alexandros; Camp, Philip J.

doi:10.1103/physreve.75.061405

Cited by 141 publications

(157 citation statements)

References 29 publications

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“…For example, the magnetization curves for a highly polydisperse magnetite ferrofluid were reproduced essentially exactly by a modified mean-field model and computer simulations of a polydisperse DHS fluid. 37,38 The paper is organized as follows. Section II contains a definition of the DHS model, the interaction potentials, and the thermodynamic parameters.…”

Section: Introductionmentioning

confidence: 99%

Theory and simulation of anisotropic pair correlations in ferrofluids in magnetic fields

Elfimova

Иванов

Camp

2012

The Journal of Chemical Physics

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Articles you may be interested inMagnetic field role on the structure and optical response of photonic crystals based on ferrofluids containing Co0.25Zn0.75Fe2O4 nanoparticles J. Appl. Phys. 115, 193502 (2014) Anisotropic pair correlations in ferrofluids exposed to magnetic fields are studied using a combination of statistical-mechanical theory and computer simulations. A simple dipolar hard-sphere model of the magnetic colloidal particles is studied in detail. A virial-expansion theory is constructed for the pair distribution function (PDF) which depends not only on the length of the pair separation vector, but also on its orientation with respect to the field. A detailed comparison is made between the theoretical predictions and accurate simulation data, and it is found that the theory works well for realistic values of the dipolar coupling constant (λ = 1), volume fraction (ϕ ≤ 0.1), and magnetic field strength. The structure factor is computed for wavevectors either parallel or perpendicular to the field. The comparison between theory and simulation is generally very good with realistic ferrofluid parameters. For both the PDF and the structure factor, there are some deviations between theory and simulation at uncommonly high dipolar coupling constants, and with very strong magnetic fields. In particular, the theory is less successful at predicting the behavior of the structure factors at very low wavevectors, and perpendicular Gaussian density fluctuations arising from strongly correlated pairs of magnetic particles. Overall, though, the theory provides reliable predictions for the nature and degree of pair correlations in ferrofluids in magnetic fields, and hence should be of use in the design of functional magnetic materials.

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Section: Introductionmentioning

confidence: 99%

Theory and simulation of anisotropic pair correlations in ferrofluids in magnetic fields

Elfimova

Иванов

Camp

2012

The Journal of Chemical Physics

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“…At intermediate values, the magnetic saturation for noninteracting permanent dipoles is predicted by Langevin theory [14] as a function of α B = mB/k B T . A recent study of ferrofluids in a uniform field [26] has shown that the noninteracting Langevin theory is still applicable in systems with moderate dipole-dipole interactions. Figure 3 shows domain morphology snapshots for simulations in which the quench was made with a uniform magnetic field present from the outset, with α B = 2 and 20 respectively and with λ = 4.…”

Section: Effect Of Uniform External Fieldmentioning

confidence: 99%

Bijels Containing Magnetic Particles: A Simulation Study

Kim¹,

Stratford

Cates³

2010

Langmuir

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Bicontinuous, interfacially jammed emulsion gels (bijels) represent a class of soft solid materials in which interpenetrating domains of two immiscible fluids are stabilized by an interfacial colloidal monolayer. Such structures can be formed by arrested spinodal decomposition from an initially single-phase colloidal suspension. Here we explore by lattice Boltzmann simulation the possible effects of using magnetic colloids in bijels. This may allow additional control over the structure, during or after formation, by application of a magnetic field or field gradient. These effects are modest for typical parameters based on the magnetic nanoparticles used in conventional ferrofluids, although significantly larger particles might be appropriate here. Field gradient effects, which are cumulative across a sample, could then allow a route for controlled breakdown of bijels as they do for particle-stabilized droplet emulsions.

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“…The finite element (FE) mesh required for the segmented brain was generated using Computer Geometry Algorithm Library (CGAL) according to previously described method (Lee et al, 2012). The relative magnetization, M rel , defined as the ratio M/M S , where M S is the saturation magnetization, was computed using standard magnetic dynamic formalism described elsewhere (Ivanov et al, 2007;Mikhaylova et al, 2004). The effect of the local electric field was modeled through the local point magnetization change according to the aforementioned linear expression for the ME effect.…”

Section: Methodsmentioning

confidence: 99%

Mapping the Brain’s electric fields with Magnetoelectric nanoparticles

et al. 2018

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Background: Neurodegenerative diseases are devastating diagnoses. Examining local electric fields in response to neural activity in real time could shed light on understanding the origins of these diseases. To date, there has not been found a way to directly map these fields without interfering with the electric circuitry of the brain. This theoretical study is focused on a nanotechnology concept to overcome the challenge of brain electric field mapping in real time. The paper shows that coupling the magnetoelectric effect of multiferroic nanoparticles, known as magnetoelectric nanoparticles (MENs), with the ultra-fast and high-sensitivity imaging capability of the recently emerged magnetic particle imaging (MPI) can enable wirelessly conducted electric-field mapping with specifications to meet the requirements for monitoring neural activity in real time. Methods: The MPI signal is numerically simulated on a realistic human brain template obtained from BrainWeb, while brain segmentation was performed with BrainSuite software. The finite element mesh is generated with Computer Geometry Algorithm Library. The effect of MENs is modeled through local point magnetization changes according to the magnetoelectric effect. Results: It is shown that, unlike traditional magnetic nanoparticles, MENs, when coupled with MPI, provide information containing electric field's spatial and temporal patterns due to local neural activity with signal sensitivities adequate for detection of minute changes at the sub-cellular level corresponding to early stage disease processes. Conclusions: Like no other nanoparticles known to date, MENs coupled with MPI can be used for mapping electric field activity of the brain at the sub-neuronal level in real time. The potential applications span from prevention and treatment of neurodegenerative diseases to paving the way to fundamental understanding and reverse engineering the brain.

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Magnetic properties of polydisperse ferrofluids: A critical comparison between experiment, theory, and computer simulation

Cited by 141 publications

References 29 publications

Theory and simulation of anisotropic pair correlations in ferrofluids in magnetic fields

Theory and simulation of anisotropic pair correlations in ferrofluids in magnetic fields

Bijels Containing Magnetic Particles: A Simulation Study

Mapping the Brain’s electric fields with Magnetoelectric nanoparticles

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