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.

铁电畴壁（Ferroelectric domain walls）凭借其迥异于体相材料（bulk material）的新奇物性，始终是科学研究的前沿热点。此前学界普遍认为畴壁的中心区域极化强度为零，但理论预测显示，畴壁会呈现出复杂的极化模式，并伴随区别于体相材料的独特相变过程。我们正研究张应变铁电薄膜中的一种相结构：当该类薄膜沉积于正交晶衬底（orthorhombic substrate）上时，其畴壁会沿单一晶体学方向定向排列。我们拟开展一项研究，利用这些宏观定向排布的畴壁阵列，探究畴壁自身的相变行为随温度的演化规律。