Dynamic Tilting of Ferroelectric Domain Walls via Optically Induced Electronic Screening

TL;DR

This study demonstrates that ultrafast optical pulses can dynamically alter the tilt orientation of ferroelectric domain walls in BaTiO3 thin films by inducing electronic screening, revealing a new method for manipulating nanoscale ferroelectricity.

Contribution

It introduces a novel approach to control ferroelectric domain wall tilting using optical excitation and electronic screening effects.

Findings

Optical pulses induce high carrier density, changing domain wall tilt angles.

Tilting occurs at 298 K with phase coexistence, but not at 343 K with single-phase.

Screening effects are enhanced by increased domain-wall charge density.

Abstract

Optical excitation perturbs the balance of phenomena selecting the tilt orientation of domain walls within ferroelectric thin films. The high carrier density induced in a low-strain BaTiO3 thin film by an above-bandgap ultrafast optical pulse changes the tilt angle that 90{\deg} a/c domain walls form with respect to the substrate-film interface. The dynamics of the changes are apparent in time-resolved synchrotron x-ray scattering studies of the domain diffuse scattering. Tilting occurs at 298 K, a temperature at which the a/b and a/c domain phases coexist but is absent at 343 K in the better ordered single-phase a/c regime. Phase coexistence at 298 K leads to increased domain-wall charge density, and thus a larger screening effect than in the single-phase regime. The screening mechanism points to new directions for the manipulation of nanoscale ferroelectricity.