On effective electric field nano-octupoling in two dimensions

Conditions towards effective electric field poling in two dimensions (2D) of octupolar molecules which can be achieved are being addressed, based on a lattice model which mimics the basic features of poling. The model is studied using the complementary approaches of analytical methods in statistical mechanics and Monte Carlo simulations. The poling field is imparted by a system of adequately shaped cylindrical electrodes. A topologically rich structure of local and global inhomogeneous octupolar order, including octupolar vortices, is present in the system. The poling criteria are shown to vary strongly throughout the cell: in close proximity to the contact points of neighboring electrodes, a high quality local octupolar order appears at temperature T ≃ 0.1 K while octupoling in the center of the cell requires temperatures as low as 10(-4) K. The highly demanding octupoling criteria are ascribed to symmetry-driven effects which decrease the quality of the octupolar phase even in the ground state, as well as to thermal fluctuations and numerical factors at above zero temperatures. Based on our results and using plausible conjectures related to the generalization of the model, it is argued that a weak global octupolar order can be reached at liquid Helium temperatures (a few Kelvins), based on current advances in optical techniques and nanotechnologies.