Mantle cloaking due to ideal magnetic dipole scattering

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.

Invisible Mie scatterer

Dielectric Mie scatterers possessing simultaneously magnetic and electric resonances can be used to tailor scattering utilizing the interference among electromagnetic multipole moments. Cloaking for this type of Mie scatterer is important for various applications. However, the existing cloaking mechanisms mainly focus on the elimination of net electric dipole moments, which have not been generalized to a Mie scatterer with both magnetic and electric responses yet. Herein, we propose and experimentally demonstrate an invisible Mie scatterer utilizing a hybrid skin cloak. The hybrid mechanism relies on the realization of a magnetic analog of a plasmonic cloak and the electric anapole condition to eliminate the net magnetic and electric dipole moments simultaneously. Microwave experiments are provided to validate the proposal. Our results not only introduce a new concept of skin cloaking for electromagnetic scatterers, but also provide new insight for the invisibility and illusion of Mie scatterers.