Fluorite-structure ferroelectrics — in particular the orthorhombic phase of HfO₂ — are of paramount interest to academia and industry because they show unprecedented scalability down to 1-nm-thick size and are compatible with Si electronics. However, their polarization switching is believed to be limited by the intrinsically high energy barrier of ferroelectric domain wall (DW) motions. Here, by unveiling a new topological class of DWs, we establish an atomic-scale mechanism of polarization switching in orthorhombic HfO₂ that exhibits unexpectedly low energy barriers of DW motion (up to 35-fold lower than given by previous conjectures). These findings demonstrate that the nucleation-and-growth-based mechanism is feasible, challenging the commonly held view that the rapid growth of the oppositely polarized domain is impossible. Building on this insight, we describe a strategy to substantially reduce the coercive fields in HfO₂-based ferroelectric devices. Our work is a crucial step towards understanding the polarization switching of HfO₂, which could provide a means to solve the key problems associated with operation speed and endurance.

萤石结构的铁电体——特别是 HfO ₂的正交相——是学术界和工业界最感兴趣的，因为它们显示出前所未有的可扩展性，小至 1 纳米厚，并且与硅电子产品兼容。然而，据信它们的极化转换受到铁电畴壁 (DW) 运动固有的高能垒的限制。在这里，通过揭示一种新的 DW 拓扑类别，我们建立了正交 HfO ₂中偏振切换的原子尺度机制这表现出出乎意料的低 DW 运动能垒（比之前的猜想低 35 倍）。这些发现表明基于成核和生长的机制是可行的，挑战了普遍认为的相反极化域的快速生长是不可能的观点。基于这一见解，我们描述了一种大大降低基于HfO ₂的铁电器件中的矫顽场的策略。我们的工作是了解 HfO ₂极化转换的关键一步，它可以提供一种方法来解决与操作速度和耐久性相关的关键问题。