标题： 铁电AlScN瞬态切换状态的原子结构 显示英文标题

标题： Atomistic Structure of Transient Switching States in Ferroelectric AlScN

摘要： 我们通过整合先进的薄膜制备、铁电切换动力学表征、高分辨率扫描透射电子显微镜（STEM）以及由基于深度神经网络的原子间势驱动的大规模分子动力学模拟，解决了纤锌矿铁电AlScN中极化翻转的微观机制。 与早期提出的瞬态非极性中间相的解释相反，我们证明了之前在STEM图像中观察到的宽过渡区域是由于180$^\circ$域壁固有的三维锯齿形形态产生的投影伪影，这是反转变换域边界的一种特征形式。 这进一步通过战略性制备的部分翻转Al$_{0.75}$Sc$_{0.25}$N薄膜的STEM成像得到证实。 我们的模拟表明，翻转过程通过集体的、逐列的原子位移进行，直接解释了锯齿形域壁的出现，并与实验中观察到的受限成核的翻转行为一致。 此外，我们表明增加Sc含量系统地降低了域壁能量和相关的成核势垒，从而降低了翻转场，这与实验趋势一致。 这些发现建立了局部域壁结构、翻转动力学和宏观铁电行为之间的直接联系。 显示英文摘要

摘要： We resolve the microscopic mechanism of polarization switching in wurtzite ferroelectric AlScN by integrating advanced thin-film fabrication, ferroelectric switching dynamics characterizations, high-resolution scanning transmission electron microscopy (STEM), and large-scale molecular dynamics simulations enabled by a deep neural network-based interatomic potential. Contrary to earlier interpretations proposing a transient nonpolar intermediate phase, we demonstrate that the broad transitional regions previously observed in STEM images are projection artifacts resulting from the intrinsic three-dimensional zigzag morphology of 180$^\circ$ domain walls, which are a characteristic form of inversion domain boundary. This is further confirmed by STEM imaging of strategically prepared, partially switched Al$_{0.75}$Sc$_{0.25}$N thin films. Our simulations reveal that switching proceeds through collective, column-by-column atomic displacements, directly explaining the emergence of zigzag-shaped domain walls, and is consistent with the nucleation-limited switching behavior observed in experimental switching dynamic measurements. Furthermore, we show that increasing Sc content systematically lowers domain wall energy and associated nucleation barrier, thereby reducing the switching field in agreement with experimental trends. These findings establish a direct connection between local domain wall structure, switching kinetics, and macroscopic ferroelectric behavior.