Self-consistent theory of nanodomain formation on non-polar surfaces of ferroelectrics

TL;DR

This paper develops a self-consistent theoretical model to describe anisotropic nanodomain formation on non-polar surfaces of ferroelectrics, accounting for crystallographic anisotropy and threshold field differences, with results matching experimental observations.

Contribution

It introduces a semi-phenomenological approach that captures the anisotropic polarization reversal dynamics induced by a charged AFM probe on ferroelectric surfaces.

Findings

Different threshold fields lead to varying domain sizes on X-, Y-, and Z-cuts.

The model explains the experimentally observed differences in nanodomain lengths.

Smaller threshold fields correspond to larger domain sizes.

Abstract

We propose a self-consistent theoretical approach capable to describe the peculiarities of the anisotropic nanodomain formation induced by a charged AFM probe on non-polar cuts of ferroelectrics. The proposed semi-phenomenological approach accounts for the difference of the threshold fields required for the domain wall motion along non-polar X- and Y - cuts, and polar Z - cut of LiNbO3. The effect steams from the fact, that the minimal distance between the equilibrium atomic positions of domain wall and the profile of lattice pinning barrier appeared different for different directions due to the crystallographic anisotropy. Using relaxation-type equation with cubic nonlinearity we calculated the polarization reversal dynamics during the probe-induced nanodomain formation for different threshold field values. The different velocity of domain growth and consequently equilibrium domain sizes on X-, Y- and Z-cuts of LiNbO3 originate from the anisotropy of the threshold field. Note that the smaller is the threshold field the larger are the domain sizes, and the fact allows explaining several times difference in nanodomain length experimentally observed on X- and Y-cuts of LiNbO3. Obtained results can give insight into the nanoscale anisotropic dynamics of polarization reversal in strongly inhomogeneous electric field.