  Carefully designed nanostructures can inspire new type of optomechanical
interactions and allow surpassing limitations set by classical diffractive
optical elements. Apart from strong near-field localization, nanostructured
environment allows controlling scattering channels and might tailor many-body
interactions. Here we investigate an effect of optical binding, where several
particles demonstrate a collective mechanical behaviour of bunching together in
a light field. In contrary to classical binding, where separation distances
between particles are diffraction limited, an auxiliary hyperbolic metasurface
is shown here to break this barrier by introducing several controllable
near-field interaction channels. Strong material dispersion of the hyperbolic
metamaterial along with high spatial confinement of optical modes, which it
supports, allow achieving superior tuning capabilities and efficient control
over binding distances on the nanoscale. In addition, a careful choice of the
metamaterial slabs thickness enables decreasing optical binding distances by
orders of magnitude compared to free space scenarios due to the multiple
reflections of volumetric modes from the substrate. Auxiliary tunable
metamaterials, which allow controlling collective optomechanical interactions
on the nanoscale, open a venue for new investigations including collective
nanofluidic interactions, triggered bio-chemical reactions and many others.
