Nanoscale piezoelectric response across a single antiparallel ferroelectric domain wall

TL;DR

This study investigates the asymmetric nanoscale piezoelectric response across a single antiparallel ferroelectric domain wall in lithium niobate, revealing defect-related effects and modeling the electromechanical behavior.

Contribution

It introduces a defect-dipole model to explain asymmetry in piezoelectric response and combines experimental microscopy with finite element simulations for analysis.

Findings

Asymmetry correlates with crystal stoichiometry.

Good agreement between experiments and simulations for near-stoichiometric samples.

Discrepancies suggest electrostatic effects and local property variations influence the response.

Abstract

Surprising asymmetry in the local electromechanical response across a single antiparallel ferroelectric domain wall is reported. Piezoelectric force microscopy is used to investigate both the in-plane and out-of- plane electromechanical signals around domain walls in congruent and near-stoichiometric lithium niobate. The observed asymmetry is shown to have a strong correlation to crystal stoichiometry, suggesting defect-domain wall interactions. A defect-dipole model is proposed. Finite element method is used to simulate the electromechanical processes at the wall and reconstruct the images. For the near-stoichiometric composition, good agreement is found in both form and magnitude. Some discrepancy remains between the experimental and modeling widths of the imaged effects across a wall. This is analyzed from the perspective of possible electrostatic contributions to the imaging process, as well as local changes in the material properties in the vicinity of the wall.