Anomalously thick domain walls in ferroelectrics
Using the Landau theory we demonstrate the possibility of unusual, anomalously thick ferroelectric domain walls, where the order parameter rotates with a nearly constant modulus as in ferromagnets. The effect occurs in 90 degrees charged domain walls and is associated with the easy polarization rotation near the morphotropic phase boundary. This magneticlike profile is unique to charged domain walls due to the availability of free charges which screen the depolarizing field resulting from polarization rotation. In contrast to previously known thick ferroelectric domain walls, the large thickness of 90 degrees charged domain walls near the morphotropic boundary is predicted for a wide temperature interval. This property may be favorable for potential applications.