Skyrmion核解决了Landauer悖论

中文摘要 AI 辅助

铁电切换是物理学中最基本且被广泛研究的对称性破缺过程之一。然而，Landauer悖论断言，理想的单畴铁电体在动力学上应不可切换，因为三维反转核会带来难以承受的退极化惩罚，导致不切实际的巨大矫顽场（切换极化所需的电场）。在此，我们表明这一长期存在的悖论由拓扑学解决。在无缺陷的PbTiO3中，大规模分子动力学模拟揭示，内在临界核是一个三维极性skyrmion。其连续的极化旋转和Néel型边界壁自补偿束缚电荷，将退极化能抑制数个数量级，并使预测的矫顽场与实验一致。这种拓扑核进一步推翻了已有60年历史的Janovec-Kay-Dunn定律。我们推导出一个解析的厚度依赖矫顽场定律，该定律由母铁电态的场致软化控制，并由单一材料描述符决定。该框架捕捉了铁电家族中多样的实验趋势，并将Kay-Dunn指数-2/3重新解释为有效的有限窗口行为。这些结果确立了极性拓扑作为内在切换的组织原则，并暗示隐藏的拓扑过渡态可能广泛塑造传统上被理解为Landau型对称性破缺的非平衡相变。

英文摘要

Ferroelectric switching is among the most fundamental and widely studied symmetry-breaking processes in physics. However, the Landauer paradox asserts that an ideal single-domain ferroelectric should be kinetically unswitchable, because a three-dimensional reversed nucleus would carry a prohibitive depolarization penalty, leading to unphysically large coercive field (the electric field required to switch the polarization). Here we show that this long-standing paradox is resolved by topology. In defect-free PbTiO3, large-scale molecular dynamics simulations reveal that the intrinsic critical nucleus is a three-dimensional polar skyrmion. Its continuous polarization rotation and Néel-type boundary walls self-compensate bound charge, suppressing the depolarization energy by orders of magnitude and bringing the predicted coercive field into agreement with experiment. This topological nucleus further overturns the 60-year-old Janovec-Kay-Dunn law. We derive an analytical thickness-dependent coercive-field law governed by field-induced softening of the parent ferroelectric state and controlled by a single material descriptor. This framework captures diverse experimental trends across ferroelectric families and recasts the Kay-Dunn exponent of -2/3 as an effective finite-window behavior. These results establish polar topology as an organizing principle for intrinsic switching and suggest that hidden topological transition states may broadly shape nonequilibrium phase transformations traditionally understood as Landau-type symmetry breaking.

发表机构

• Department of Physics, School of Science, Westlake University（西湖大学理学院物理系）
• Institute of Natural Sciences, Westlake Institute for Advanced Study（西湖高等研究院自然科学研究院）

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