抄録
Thickness dependence of the coercive field (Ec) in ferroelectric thin films has been numerically simulated using the four-states Potts model. In this model, four mutually perpendicular dipole-orientations result in four different kinds of domains. The rotation of each dipole is restricted only to 90°, either clockwise or counter-clockwise. The thickness dependence is induced by the influence of the surface dipoles. These dipoles have slightly different physical parameters due to the interfacial effects. The simulation result shows the existence of a maximum coercive field at the critical thickness (dc) for the Ec against d curve. For the thickness d<dc, Ec increases with d. On the other hand, for d>dc, an opposite trend can be obtained.
