(a) Total electric (top) and longitudinal magnetic (bottom) field maps of an APB with w₀ = 0.9 λ carrying 3 mW power [16]. (b) Schematic of an APB with longitudinal magnetic field illuminating two clusters of silver nanospheres or two high density dielectric spheres (e.g., two Si nanospheres). The two magnetic meta-atoms exert a near-field photo-induced force on each other [12,13]. (c) The electric and magnetic time-average forces acting on the top meta-atom (the clusters of plasmonic nanoparticles) located on the beam axis as function of wavelength. The APB has the beam waist parameter w₀ = 0.9 λ and 3 mW power. A significant attractive magnetic part of the Lorentz force is present [13].