Disentangling stress and curvature effects in layered 2D ferroelectric CuInP2S6

TL;DR

This paper investigates how local curvature and strain influence the ferroelectric properties of 2D CuInP2S6, combining experimental microscopy with modeling to understand and manipulate its polarization behavior for nanoelectronic applications.

Contribution

It introduces a finite element Landau-Ginzburg-Devonshire model to decouple curvature and strain effects in 2D ferroelectric CuInP2S6, revealing how bending induces ferrielectric domains and affects hysteresis.

Findings

Bending induces ferrielectric domains in CIPS.

Polarization-voltage hysteresis differs between bending and non-bending regions.

Flexoelectric effect influences local polarization hysteresis.

Abstract

Nanoscale ferroelectric 2D materials offer unique opportunity to investigate curvature and strain effects on materials functionalities. Among these, CuInP2S6 (CIPS) has attracted tremendous research interest in recent years due to combination of room temperature ferroelectricity, scalability to a few layers thickness, and unique ferrielectric properties due to coexistence of 2 polar sublattices. Here, we explore the local curvature and strain effect on the polarization in CIPS via piezoresponse force microscopy and spectroscopy. To explain the observed behaviors and decouple the curvature and strain effects in 2D CIPS, we introduce finite element Landau-Ginzburg-Devonshire model. The results show that bending induces ferrielectric domains in CIPS, and the polarization-voltage hysteresis loops differ in bending and non-bending regions. Our simulation indicates that the flexoelectric effect can affect local polarization hysteresis. These studies open a novel pathway for the fabrication of curvature-engineered nanoelectronic devices.