Phenomenological description of bright domain walls in ferroelectric-antiferroelectric layered chalcogenides

TL;DR

This paper provides a phenomenological model explaining the physical mechanisms behind bright and dark domain walls in layered ferroelectric-antiferroelectric materials, highlighting their local piezoresponse variations.

Contribution

It introduces a Landau-Ginzburg-Devonshire phenomenological framework combined with a four sub-lattices model to describe domain wall contrast in layered ferroics.

Findings

Quantitative description of bright and dark domain boundaries

Explanation of local piezoresponse enhancement at domain walls

Application to layered CuInP2(S1-ySey)6 materials

Abstract

Recently, a layered ferroelectric CuInP2Se6 was shown to exhibit domain walls with locally enhanced piezoresponse - a striking departure from the observations of nominally zero piezoresponse in most ferroelectrics. Although it was proposed that such "bright" 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 four sub-lattices 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-ySey)6