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

Abstract

Recently, a layered ferroelectric CuInP2Se6 was shown to exhibit domain walls with locally enhanced piezoresponsea 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 ferriand 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 (0y 1).

A combined theoretical and experimental study of the phase coexistence and morphotropic boundaries in ferroelectric-antiferroelectric-antiferrodistortive multiferroics

“…Note that the free energy relief transforms into a thin cross for the case 𝜒 ≫ 1 and |𝜖| ≪ 1. Except for the calculated in this work mixed AFE-FE state located in the region 𝜒 > Note that an LGD-type phenomenological model can describe the shape of the multi-well potential, but the microscopic origin of the order parameter(s), which form this potential, is not explained by the model FE-AFE state [58]. The main result of this section is the prediction of different 3D AFE-type long-range ordered phases in AFD multiferroics, such as Bi1-yRyFeO3.…”

Stress-induced phase transitions in nanoscale CuInP2S6

“…order parameters [38,39]. Note that the inclusion of 𝛿 8 𝑃 3 8 is mandatory for the stability of thermodynamic potential (1), because 𝛾 < 0 in the considered case.…”

“…The CuInP2(S,Se)6 family reveals very unusual features of a nonlinear dielectric response indicating that a spontaneous polarization may exist above the transition temperature [32], extremely large elastic nonlinearity in the direction perpendicular to the layers [33,34], a giant negative electrostriction and dielectric tunability [35], the electrostriction induced piezoelectricity above the ferroelectric transition temperature [36], morphotropic phase transitions between its monoclinic and trigonal phases [37], and anomalous "bright" domain walls with enhanced local piezoelectric response [38,39].…”

Anharmonic stabilization of ferrielectricity in CuInP$_2$Se$_6$

“…Of those, the transition metal thiophosphates are a promising family of materials that host out-of-plane ferrielectricity (FiE) with large values of polarization [6,11,12]. Further, research efforts in these materials have reported a plethora of properties including negative piezoelectricity, negative electrostriction, large dielectric tunability, and unconventional field-induced switching behavior, all of which depend strongly on the polarization [13][14][15][16][17][18][19][20][21][22][23]. Despite the growing interest, a clear understanding of the origin and stabilization of the polar phase is still lacking in transition metal thiophosphate.…”