Two Dimensional Monte Carlo Simulations of Aggregation Phenomena in Ferromagnetic Colloidal Dispersions Composed of Rod-Like Hematite Particles

2007 ◽  
Author(s):  
Yuta Katayama ◽  
Ryo Hayasaka ◽  
Akira Satoh
Keyword(s):  
Monte Carlo ◽  
Magnetic Moment ◽  
Pair Correlation ◽  
Colloidal Dispersions ◽  
Magnetic Interactions ◽  
Particle Interactions ◽  
Two Dimensional ◽  
Internal Structures ◽  
The Magnetic Field ◽  
Aggregation Phenomena

We have investigated aggregation phenomena of ferromagnetic colloidal dispersions composed of rod-like hematite particles which have a magnetic moment normal to the particle axis, by means of the cluster-moving Monte Carlo method. In concrete, we have treated a two-dimensional dispersion in order to clarify the influences of the particle aspect ratio, magnetic interactions between particles, and the magnetic field strength on particle aggregations. Internal structures of particle aggregates have been discussed quantitatively in terms of radial distribution, pair correlation, orientational pair correlation functions, and number distributions of clusters. The results obtained here are summarized as follows. Rod-like particles tend to aggregate to form raft-like clusters more significantly along the magnetic moment direction as magnetic particle-particle interactions increase. However, such raft-like clusters do not aggregate further to form thicker clusters, which is in significantly contrast to dispersions of spherical or rod-like particles with a magnetic moment along the particle axis.

Quasi-2D Monte Carlo Simulations of a Colloidal Dispersion Composed of Magnetic Plate-Like Particles With Magnetic Moment Normal to the Particle Axis

2008 ◽  
Author(s):  
Akira Satoh ◽  
Yasuhiro Sakuda
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Field Strength ◽  
Monte Carlo Simulations ◽  
Magnetic Field Strength ◽  
Magnetic Moment ◽  
Colloidal Dispersion ◽  
Magnetic Interactions ◽  
The Magnetic Field ◽  
Aggregation Phenomena

We have investigated aggregation phenomena of a colloidal dispersion composed of magnetic plate-like particles by means of Monte Carlo simulations. Such plate-like particles have been modeled as disk-like particles which have a magnetic moment normal to the particle axis at the particle center, with the section shape of a spherocylinder. The main objective of the present study is to clarify the influences of magnetic field strength and magnetic interactions between particles on particle aggregation phenomena. We have concentrated our attention on a quasi-2D system from an application point of view such as development of surface changing technology using such magnetic plate-like particles. A magnetic field was applied along a direction perpendicular to the plane of the monolayer. Internal structures of particle aggregates have been discussed quantitatively in terms of radial distribution and orientational pair correlation functions. The main results obtained here are summarized as follows. For the case of strong magnetic interactions between particles, the particles form long column-like clusters with their magnetic moments alternating in direction between the neighboring particles. These tendencies appear under circumstances of a weak applied magnetic field. However, as the magnetic field strength increases, the particles incline toward the magnetic field direction, so that the particles do not form such clusters.

3D Monte Carlo Simulations of Aggregate Structures in a Magnetic Colloidal Suspension Composed of Plate-Like Particles With Magnetic Moment Normal to the Particle Axis

2010 ◽  
Author(s):  
Yasuhiro Sakuda ◽  
Masayuki Aoshima ◽  
Akira Satoh
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Applied Magnetic Field ◽  
Magnetic Moment ◽  
Magnetic Particle ◽  
Colloidal Suspension ◽  
Magnetic Moments ◽  
Particle Interactions ◽  
Aggregate Structures ◽  
The Magnetic Field

We have investigated the internal aggregate structures of a colloidal suspension composed of magnetic plate-like particles with a magnetic moment normal to the particle axis by means of three-dimensional Monte Carlo simulations. In concrete, we have attempted to clarify the influences of the magnetic field strength, magnetic interactions between particles, and volumetric fraction of particles, on particle aggregation phenomena. In order to discuss quantitatively the aggregate structures of particles, we have focused on the radial distribution and orientational pair correlation function. For no applied magnetic field cases, long column-like clusters are formed as magnetic particle-particle interactions increase. Characteristics of these clusters are that particles incline in a certain direction with their magnetic moments alternating in direction between the neighboring particles. For applied magnetic field cases, the magnetic moments of the particles incline in the magnetic field direction, so that the columnar clusters are not formed. The brick wall-like aggregates are formed as the influences of the magnetic field and magnetic particle-particle interactions become significantly dominant.

Molecular Dynamics Study of the Effect of Magnetic Field on the Static and Dynamical Properties of Two-Dimensional Coulomb Systems

1997 ◽  
Vol 492 ◽  
Author(s):  
Godfrey Gumbs ◽  
Girija S. Dubey
Keyword(s):  
Magnetic Field ◽  
Molecular Dynamics ◽  
Correlation Function ◽  
External Magnetic Field ◽  
Pair Correlation ◽  
Mean Square Displacement ◽  
Coulomb Systems ◽  
First Principles Calculation ◽  
Two Dimensional ◽  
The Magnetic Field

ABSTRACTMolecular dynamics simulations are used to examine the effect of a uniform perpendicular magnetic field on a two-dimensional (2D) interacting electron system and we analyze how the magnetic field affects the single-particle properties of the system. In this simulation, we include the effect of the magnetic field classically through the Lorentz force. Both the Coulomb interaction and the magnetic field are included directly in the electron dynamics to study their combined effect on the transport properties of the 2D system. Results are presented for the pair correlation function, the mean square displacement and the density correlation function, in the presence and absence of an external magnetic field. Our simulation results, obtained from a first-principles calculation, clearly show that the external magnetic field has no effect on the static properties, but it affects the dynamics.

Influences of Magnetic Particle-Particle Interactions on Orientational Distributions and Rheological Properties of a Semi-Dense Colloidal Dispersion Composed of Rod-Like Hematite Particles: Analysis by Means of Mean Field Approximation for an External Magnetic Field Parallel to the Angular Velocity Vector of a Simple Shear Flow

2007 ◽  
Author(s):  
Ryo Hayasaka ◽  
Masayuki Aoshima ◽  
Toshinori Suzuki ◽  
Akira Satoh
Keyword(s):  
Magnetic Field ◽  
Magnetic Moment ◽  
Mean Field ◽  
Field Approximation ◽  
Field Direction ◽  
Magnetic Interactions ◽  
Mean Field Approximation ◽  
Magnetic Field Direction ◽  
Orientational Distribution ◽  
The Magnetic Field

We have investigated mainly the influences of magnetic particle-particle interactions on orientational distributions and viscosity of a semi-dense dispersion, which is composed of rod-like particles with a magnetic moment magnetized normal to the particle axis. In addition, the influences of the magnetic field strength, shear rate, and random forces on the orientational distribution and rheological properties have been clarified. The mean field approximation has been applied to take into account magnetic interactions between rod-like particles. The basic equation of the orientational distribution function has been derived from the balance of torques and solved by the numerical analysis method. The results obtained here are summarized as follows. For a strong magnetic field, the rotational motion of the rod-like particle is restricted in a plane normal to the shearing plane because the magnetic moment of the particle is restricted in the magnetic field direction. Under circumstances of a very strong magnetic interaction between particles, the magnetic moment is strongly restricted in the magnetic field direction, so that the particle has a tendency to incline in the flow direction with the magnetic moment pointing to the magnetic field direction. For a strong shear flow, a directional characteristic of rod-like particles is enhanced, and this leads to a more significant one-peak-type distribution of the orientational distribution function. Magnetic interactions between particles do not contribute to the viscosity because the mean-field vector has only a component along the magnetic field direction.

Brownian Dynamics Simulations of Colloidal Dispersion Composed of Ferromagnetic Spherocylinder Particles in a Simple Shear Flow (For the Case of an Applied Magnetic Field Normal to the Shear Plane)

2009 ◽  
Author(s):  
Ryo Hayasaka ◽  
Yasuhiro Sakuda ◽  
Akira Satoh
Keyword(s):  
Magnetic Field ◽  
Brownian Dynamics ◽  
Magnetic Particle ◽  
Colloidal Dispersion ◽  
Magnetic Interactions ◽  
Simple Shear Flow ◽  
Particle Interactions ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations ◽  
The Magnetic Field

We have investigated aggregate structures and rheological properties of a colloidal dispersion composed of ferromagnetic spherocylinder particles with a magnetic moment along the particle axis direction, by means of Brownian dynamics simulations. In concrete, we have attempted to clarify the influences of the flow field, magnetic field strength, magnetic interactions between particles and volumetric fraction of particles. In order to discuss quantitatively the internal structures of clusters, we have concentrated our attention on the radial distribution and orientational distribution functions. The present results are compared with those of the theoretical analysis for dilute dispersions and also non-dilute dispersions; the results for the latter were obtained by means of the mean-field approximation, which magnetic particle-particle interactions can be taken into account. Some important results are summarized as follows. For the case of the magnetic field strength and magnetic interactions between particles are more dominant than the viscous forces due to a simple shear flow, chain-like like clusters are formed along the magnetic field direction, although they are slightly tilted to the flow direction. When magnetic particle-particle interactions become over a certain value, such cluster formation leads to a significant increase in the viscosity of the dispersion.

Phase Transition in 2D Anisotropic Ising Model with Next-Nearest Neighbor Interactions in a Magnetic Field

SPIN ◽  
2018 ◽  
Vol 08 (03) ◽  
pp. 1850010
Author(s):  
D. Farsal ◽  
M. Badia ◽  
M. Bennai
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Monte Carlo ◽  
Magnetic Susceptibility ◽  
Critical Temperature ◽  
Ising Model ◽  
Nearest Neighbor ◽  
Two Dimensional ◽  
The Magnetic Field

The critical behavior at the phase transition of the ferromagnetic two-dimensional anisotropic Ising model with next-nearest neighbor (NNN) couplings in the presence of the field is determined using mainly Monte Carlo (MC) method. This method is used to investigate the phase diagram of the model and to verify the existence of a divergence at null temperature which often appears in two-dimensional systems. We analyze also the influence of the report of the NNN interactions [Formula: see text] and the magnetic field [Formula: see text] on the critical temperature of the system, and we show that the critical temperature depends on the magnetic field for positive values of the interaction. Finally, we have investigated other thermodynamical qualities such as the magnetic susceptibility [Formula: see text]. It has been shown that their thermal behavior depends qualitatively and quantitatively on the strength of NNN interactions and the magnetic field.

scholarly journals MONTE CARLO SIMULATION OF NUCLEATION IN THE TWO-DIMENSIONAL POTTS MODEL

2002 ◽  
Vol 13 (04) ◽  
pp. 495-508 ◽  
Author(s):  
S. B. RUTKEVICH
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Field Dependence ◽  
Potts Model ◽  
Magnetic Field Dependence ◽  
Nucleation Theory ◽  
Temperature Phase ◽  
Two Dimensional ◽  
Nucleation Time ◽  
The Magnetic Field

Nucleation in the two-dimensional q-state Potts model has been studied by means of Monte Carlo simulations using the heat-bath dynamics. The initial metastable state has been prepared by magnetic quench of the ordered low-temperature phase. The magnetic field dependence of the nucleation time has been measured as the function of the magnetic field for different q and lattice sizes at T = 0.5Tc. A size-dependent crossover from the coalescence to nucleation region is observed at all q. The magnetic field dependence of the nucleation time is roughly described by the classical nucleation theory. Our data show increase of the anisotropy in the shape of the critical droplets with increase of q.

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