Percolation and orientational ordering in systems of magnetic nanorods

Alvarez, Carlos Eduardo Mendez; Klapp, Sabine H. L.

doi:10.1039/c2sm25636c

Cited by 26 publications

(32 citation statements)

References 59 publications

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“…The novel aspects of our contribution are the following. While others have investigated how the rod aspect ratio affects the phase behavior 27,34 we instead focus solely on the internal charge separation. We find that coarse gel-like structures form at high charge separations while denser aggregates form at low charge separations.…”

Section: Discussionmentioning

confidence: 99%

“…26 Alvarez and Klapp applied Monte Carlo simulations to systems of dipolar rods with permanent magnetic dipole moments modeled as fused magnetic dipolar spheres. 27 Additionally, they investigated rod-like particles with a longitudinal point dipole and found clusters of parallel rods as we do in our simulations at low charge distances. 28 Miller et al used molecular dynamics to investigate systems of dipolar dumbbells, representing the dipole-dipole interaction by a combination of a soft-sphere interaction and Coulombic interaction, and found that these particles aligned into head-to-tail chains.…”

Section: Introductionmentioning

confidence: 99%

“…While others have investigated dipolar colloidal rods through simulation, the focus has usually been on how the aspect ratio of the rod affects the phase behavior 27,34 instead of how the internal charge separation affects the phase behavior, as we focus on in this work. A key consideration in the types of assemblies that form is the alignment of the particles at different conditions.…”

Section: Introductionmentioning

confidence: 99%

“…A pair of rods can in general align in two orientations: either head-to-tail or side-by-side. 26,27,34 In our model a shift between these two orientations occurs when the charge separation is varied. The exact charge separation value that defines the boundary between these two orientations depends on both the aspect ratio of the rod and the expression for the potential energy of interaction between the electric charges, herein represented by a screened Coulomb potential, i.e.…”

Section: Introductionmentioning

confidence: 99%

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The effect of charge separation on the phase behavior of dipolar colloidal rods

et al. 2016

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a Colloids with anisotropic shape and charge distribution can assemble into a variety of structures that could find use as novel materials for optical, photonic, electronic and structural applications. Because experimental characterization of the many possible types of multi-shape and multipolar colloidal particles that could form useful structures is difficult, the search for novel colloidal materials can be enhanced by simulations of colloidal particle assembly. We have simulated a system of dipolar colloidal rods at fixed aspect ratio using discontinuous molecular dynamics (DMD) to investigate how the charge separation of an embedded dipole affects the types of assemblies that occur. Each dipolar rod is modeled as several overlapping spheres fixed in an elongated shape to represent excluded volume and two smaller, embedded spheres to represent the charges that make up the extended dipole. Large charge separations predominately form structures where the rods link head-to-tail while small charge separations predominately form structures where the rods stack side-by-side. Rods with small charge separations tend to form dense aggregates while rods with large charge separations tend to form coarse gel-like structures. Structural phase boundaries between fluid, string-fluid, and ''gel'' (networked) phases are mapped out and characterized as to whether they have global head-to-tail or global side-by-side order. A structural coarsening transition is observed for particles with large charge separations in which the head-tail networks thicken as temperature is lowered due to an increased tendency to form side-by-side structures. Triangularly connected networks form at small charge separations; these may be useful for encapsulating smaller particles.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of charge separation on the phase behavior of dipolar colloidal rods

et al. 2016

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“…In recent years, many types of unusual magnetic systems have been studied. Among them are magnetic rods and ellipsoids, 63,64 magnetic core-shell particles, 65 extended dipoles in the form of two overlapping, oppositely charged spheres, 66 linear molecules with shifted dipoles, 67 particles with magnetic caps, 68 particles interacting by higher moments then dipoles, 69 shifted-dipole particles moving in precessing magnetic fields, 70 and particles with embedded magnetic cubes. 71 Recently, we proposed an alternative way for creating a system with "unusual" properties.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and magnetic properties of magnetic fluids consisting of shifted dipole particles under the influence of an external magnetic field

Weeber

Klinkigt²,

Kantorovich³

et al. 2013

The Journal of Chemical Physics

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Articles you may be interested inTheory of magnetic fluid heating with an alternating magnetic field with temperature dependent materials properties for self-regulated heating J. Appl. Phys. 105, 07B324 (2009) We investigate the structure of a recently proposed magnetic fluid consisting of shifted dipolar (SD) particles in an externally applied magnetic field via computer simulations. For standard dipolar fluids the applied magnetic field usually enhances the dipole-dipole correlations and facilitates chain formation whereas in the present system the effect of an external field can result in a break-up of clusters. We thoroughly investigate the origin of this phenomenon through analyzing first the ground states of the SD-particle systems as a function of an applied field. In a second step we quantify the microstructure of these systems as functions of the shift parameter, the effective interaction parameter, and the applied magnetic field strength. We conclude the paper by showing that with the proper choice of parameters, it is possible to create a system of SD-particles with highly interacting magnetic particles, whose initial susceptibility is below the Langevin susceptibility, and which remains spatially isotropic even in a very strong external magnetic field. © 2013 AIP Publishing LLC.

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Modeling Magnetic Particles

Satoh

2015

Wiley Encyclopedia of Electrical and Electronics Engineering

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Since there are various strategies in performing simulations at a microscopic level to obtain reliable results, we here discuss the modeling of magnetic particles, simulation techniques, and related tactics such as criterion of particle overlap: the particle overlap will certainly become a serious hurdle to develop a successful and reliable computational code of simulations in treating the motion of magnetic particles in a suspension. One example of simulations based on Brownian dynamics method is shown in order for nonexpert readers to straightforwardly understand how the simulation techniques play an important role in analyzing the microscopic behavior of magnetic particles in an applied magnetic field (as well as a shear flow). In the following sections, we first discuss the modeling of magnetic particles, the different axis systems grasping the particle situations, the criterion of particle overlap, simulation methods of Brownian dynamics and lattice Boltzmann method, and finally application of Brownian dynamics method to magnetic particle suspensions.

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Percolation and orientational ordering in systems of magnetic nanorods

Cited by 26 publications

References 59 publications

The effect of charge separation on the phase behavior of dipolar colloidal rods

The effect of charge separation on the phase behavior of dipolar colloidal rods

Microstructure and magnetic properties of magnetic fluids consisting of shifted dipole particles under the influence of an external magnetic field

Modeling Magnetic Particles

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