HYSTERESIS IN ELECTRIC-DIPOLE MONOLAYERS

The possibility of hysteretic behaviours in plane monolayers of electr ic dipoles is investigated. The basic tool for this study is a model w here the electric dipoles can rotate around the nodes of a plane rhomb ic grid and the electric interactions among dipoles are properly simpl ified (Union Jack approximation). In the ideal case of an infinitely e xtending monolayer, the model yields analytical solutions both for the spatially periodical equilibrium orientations of dipoles and for thei r stability under the influence of an external electric field. On this basis, a set of hysteresis cycles dealing with different physical sit uations is obtained and discussed. Then, the much more realistic and c omplex case of finite-size dipole- monolayers is considered and the hy steresis cycles are obtained by computer calculations. The degree of s imilarity of these numerical results with the analytical ones of the c orresponding infinitely extending monolayers puts into evidence the pr ediction capabilities of such simple model.