  In the framework of the Landau-Ginzburg-Devonshire (LGD) approach, we studied
the possibility of controlling the polarity and chirality of equilibrium domain
structures by a homogeneous external electric field in a nanosized
ferroelectric core covered with an ultra-thin shell of screening charge. Under
certain screening lengths and core sizes, the minimum of the LGD energy, which
consists of Landau-Devonshire energy, Ginzburg polarization gradient energy,
and electrostatic terms, leads to the spontaneous appearance of stable
labyrinth domain structures in the core. The labyrinths evolve from an initial
polarization distribution consisting of arbitrarily small randomly oriented
nanodomains. The equilibrium labyrinth structure is weakly influenced by
details of the initial polarization distribution, such that one can obtain a
quasi-continuum of nearly degenerate labyrinth structures, whose number is
limited only by the mesh discretization density. Applying a homogeneous
electric field to a nanoparticle with labyrinth domains, and subsequently
removing it, allows inducing changes to the labyrinth structure, as the maze
polarity is controlled by a field projection on the particle polar axis. Under
specific conditions of the screening charge relaxation, the quasi-static
dielectric susceptibility of the labyrinth structure can be negative,
potentially leading to a negative capacitance effect. Considering the general
validity of the LGD approach, we expect that an electric field control of
labyrinth domains is possible in many spatially-confined nanosized ferroics,
which can be potentially interesting for advanced cryptography and modern
nanoelectronics.

Materials Science;Mesoscale and Nanoscale Physics