Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 67000 Strasbourg, France.
DQMP, University of Geneva, 24 Quai Ernest Ansermet, 1211 Geneva, Switzerland.
Nat Commun. 2017 Jun 8;8:15768. doi: 10.1038/ncomms15768.
The properties of ferroelectric domain walls can significantly differ from those of their parent material. Elucidating their internal structure is essential for the design of advanced devices exploiting nanoscale ferroicity and such localized functional properties. Here, we probe the internal structure of 180° ferroelectric domain walls in lead zirconate titanate (PZT) thin films and lithium tantalate bulk crystals by means of second-harmonic generation microscopy. In both systems, we detect a pronounced second-harmonic signal at the walls. Local polarimetry analysis of this signal combined with numerical modelling reveals the existence of a planar polarization within the walls, with Néel and Bloch-like configurations in PZT and lithium tantalate, respectively. Moreover, we find domain wall chirality reversal at line defects crossing lithium tantalate crystals. Our results demonstrate a clear deviation from the ideal Ising configuration that is traditionally expected in uniaxial ferroelectrics, corroborating recent theoretical predictions of a more complex, often chiral structure.
铁电畴壁的性质可能与母体材料有显著差异。阐明其内部结构对于设计利用纳米级铁电性和局部功能特性的先进器件至关重要。在这里，我们通过二次谐波产生显微镜探测了锆钛酸铅（PZT）薄膜和钽酸锂体块晶体中 180°铁电畴壁的内部结构。在这两个系统中，我们在壁处检测到明显的二次谐波信号。对该信号的局部极角分析结合数值模拟揭示了壁内存在平面极化，在 PZT 和钽酸锂中分别具有奈尔和布洛赫型构型。此外，我们发现穿过钽酸锂晶体的线缺陷处畴壁手性反转。我们的结果表明，与传统上在单轴铁电体中预期的理想伊辛构型存在明显偏差，这证实了最近关于更复杂、通常是手性结构的理论预测。
