  Using a free-energy based computational model, we have investigated the
response of a system comprising two interacting ferroelectric nanospheres,
embedded in a dielectric medium, to a static external electric field. The
system response is hysteretic and tunable by changing the inter-particle
distance and the orientation of the applied field, which strongly modulates the
field-driven long-range elastic interactions between the particles that
propagate through the dielectric matrix. At small separations, the sensitivity
of the system behavior with respect to the electric field direction originates
from drastically different configurations of the local vortex-like polarization
states in ferroelectric particles. This suggests new routes for the design of
composite metamaterials whose dielectric properties can be controlled and tuned
by selecting the mutual arrangement of their ferroelectric components.
