Synergistic interactions of binary suspensions of magnetic anisotropic particles.

We report the effect of the dipole-dipole interaction and shape anisotropy in suspensions of permanently magnetized anisotropic particles. We quantify the dipolar interaction energy using an ellipsoid-dipole model to describe particles with similar or dissimilar shapes. The expression captures the physics of the point-dipole interaction energy between uniformly magnetized spherical particles. Additionally, we report Monte Carlo simulations to describe the effect of dipolar interaction and shape anisotropy under different field strengths. Results show that the shape anisotropy and dipolar interactions modify the head-to-tail interaction with respect to spheres, promoting dendritic and barbed-wire structures in uniform ellipsoids and binary mixtures, respectively. Furthermore, competing entropic and energy interactions generate a synergistic effect reducing the magnetic response of binary suspensions.