System of particles with shifted magnetic dipoles

Abstract

Two-dimensional calculations of the meniscus of a magnetic fluid around a currentcarrying vertical and cylindrical wire are presented. The influence of the viscosity, the angle of contact at the wire and at the rim of the vessel are studied. Based on the material properties of an experimentally used magnetic fluid, the numerically determined meniscus is compared with the experimentally measured one. The comparison is made for a linear law of magnetization as well as for the experimentally measured nonlinear magnetization curve.

Phase polarity in a ferrofluid monolayer of shifted-dipole spheres

“…Thus, upon averaging, an aggregation mechanism which is effective on few particles is replaced by a collective mechanism tending to the same global ordering effect. This is confirmed by some kind of anomalous behaviour already observed in simulations 9 of assemblies of shifted-dipole particles at rather high densities and shift a in the range 0.7-0.8. The formation of compact clusters with non-zero remnant magnetization is eventually reflected in the thermodynamic properties of continuum phases.…”

“…Here we envision a nanoparticle as bearing a point magnetic dipole m located inside it. We shall, however, abandon the classical model case of a spherical nanoparticle with a (point) dipole in its center; rather, with the aim of mimicking more complex nanoparticles that have become accessible to experiments, [3][4][5][6] we shall adopt a model recently suggested and studied by C. Holm and his co-workers, [7][8][9] where the inner dipole is radially oriented away from the sphere's center. In short, these particles are also called shifted-dipole spheres.…”

“…† Ferrofluids are currently being extensively studied for the many applications they promise to have in diverse fields, ranging from engineering to medicine. 9,[16][17][18] It is not surprising that a vast literature already exists, both experimental and theoretical. Concerning this latter, we shall be contented here with referring the reader to a rather comprehensive review, 19 mainly dealing with three-dimensional systems, and to a shorter review, 20 mainly focussing on computer simulations.…”

An analytic mean-field model for the magnetic response of a ferrofluid monolayer

“…[1][2][3] Here we model a ferrouid as a collection of hard spheres, each bearing a point dipole, possibly shied from the sphere's center, and oriented radially. This model has recently been introduced and intensively studied by Holm and coworkers, [4][5][6] who have mainly considered arrangements of such particles in monolayers. Traditionally, ferrouids are systems far more complex than that, but there are at least two reasons that make a ferrouid monolayer worthy of consideration.…”

“…A lower dimensionality also plays a role in many possible applications of ferrouids, ranging from engineering to medicine. [6][7][8][9][10] In particular, the ferromagnetic behavior of a layer of nanoparticles deposited on a targeted organ has potential applications in theranostics, 11 a new medical discipline, thus named by Warner, 12 bridging diagnosis and therapy.…”