  The formation of a stable magneto plasmonic dimer with THz resonances is
theoretically studied for the principal directions of the system. Unlike a
recent report, our work provides a complete description of the full photonic
coupling for arbitrary magnetic fields as, for instance, unbalanced particle
spins. As an illustration, we consider two small, n-doped InSb nanoparticles
under illumination by two counter-propagating plane waves. Remarkably, when an
external magnetic field exists, the symmetry in the system is broken, and a
resonant radiation pressure for the dimer appears. Similarly, tunable
inter-particle forces and spins are exerted on the non-reciprocal dimer. The
system is also characterized when the magnetic field is absent. Moreover, we
show how the mechanical observables truly characterize the dimer since their
resonance dependency contains detailed information about the system. Unlike
far-field observables like absorption, mechanical magnitudes depend on the
system's near-field. In addition, the nature of the particle spins is
originally explained by the energy flow's behavior around the dimer. This work
constitutes a generalization of any previous approach to optical binding
between small nanoparticles. It paves the way for fully controlling optical
matter and nano factory designs based on surface plasmon polaritons.
