Abstract
Recently, a layered ferroelectric CuInP2Se6 was shown to exhibit domain walls with locally enhanced piezoresponse鈥攁 striking departure from the observations of nominally zero piezoresponse in most ferroelectrics. Although it was proposed that such 鈥渂right鈥� domain walls are phase boundaries between ferri- and antiferroelectrically ordered regions of the materials, the physical mechanisms behind the existence and response of these boundaries remain to be understood. Here, using Landau-Ginzburg-Devonshire phenomenology combined with a four sublattices model, we describe quantitatively the bright-contrast and dark-contrast domain boundaries between the antiferroelectric, ferroelectric, or ferrielectric long-range-ordered phases in a layered ferroelectric-antiferroelectric ferroics, such as CuInP2(S1鈭抷Sey)6.
