Probing phase transitions in ferroelectric domain walls with x-ray diffraction

Ferroelectric domain walls have been at the forefront of scientific research due to their novel properties that are often different from the bulk material. Domain walls were originally believed to have zero polarisation at their centre, but theoretical predictions have shown that they exhibit complex polarisation patterns with unique phase transitions that are distinct from the bulk material. We are studying a phase in tensile-strained ferroelectric thin films in which domain walls are aligned along one crystallographic direction when deposited on an orthorhombic substrate. We propose a study in which we take advantage of these macroscopically-aligned domain wall arrays to probe phase transitions within the domain walls themselves as a function of temperature.