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We report the effect of shape anisotropy and material properties on the directed assembly of binary suspensions composed of magnetizable ellipsoids. In a Monte Carlo simulation, we implement the ellipsoid-dipole model to calculate the pairwise dipolar interaction energy as a function of position and orientation. The analysis explores dilute suspensions of paramagnetic and diamagnetic ellipsoids with different aspect ratios in a superparamagnetic medium. We analyze the local order of binary structuresas a function of particle aspect ratio, medium permeability, and dipolar interaction strength. Our results show that local order and symmetry are tunable under the influence of a uniform magnetic field when one component of the structure is dilute with respect to the other. The simulation results match previously reported experiments on the directed assembly of binary suspension of spheres. Additionally, we report the conditions on particle aspect ratios and medium properties for various structures with rotational symmetries, as well as open and enclosed structures under the influence of a uniform magnetic field.
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This content will become publicly available on August 13, 2026
The ellipsoid-dipole model. Theoretical fundamentals and applications
We report the fundamental theoretical framework of the ellipsoid-dipole model and its applicability in quantifying the pairwise dipolar energy between ellipsoids with different sizes, aspect ratios, and magnetic properties. Additionally, we discuss the limitations of the model and its potential for describing interacting ellipsoids undervarious field conditions for both established and emerging applications. We analyze the dipolar interaction energy of suspensions composed of different pairs of magnetic ellipsoids, including permanently magnetized ellipsoids, paramagnetic ellipsoids, diamagnetic ellipsoids, and mixtures of them. We validate the results of the ellipsoid-dipole model and the corresponding pairwise dipolar interaction energy against those produced by the point-dipole approximation. Furthermore, we quantify the relative equilibrium positions and orientations of different ellipsoid pairs in a uniform magnetic field. The article shows that the ellipsoid-dipole model offers a wide range of possibilities for predicting and engineering colloidal suspensions composed of binary ellipsoids and for enhancing current applications.
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- Award ID(s):
- 2338064
- PAR ID:
- 10652657
- Publisher / Repository:
- Soft Matter
- Date Published:
- Journal Name:
- Soft Matter
- Volume:
- 21
- Issue:
- 32
- ISSN:
- 1744-683X
- Page Range / eLocation ID:
- 6432 to 6451
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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