铁电Hf0.5Zr0.5O2极化切换中的瞬态迂回与协同氧交换
Transient Detour and Cooperative Oxygen Exchange in the Polarization Switching of Ferroelectric Hf0.5Zr0.5O2
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中文总结 AI 辅助
本研究通过电场诱导分子动力学模拟揭示铁电Hf0.5Zr0.5O2的极化切换由O3c与O4c的动态交换驱动，明确其独特的瞬态迂回机制及内部自补偿效应，为下一代铁电存储器设计提供关键依据。
中文摘要 AI 辅助
氧化铪锆（HZO）因超薄膜区域优异的铁电性及CMOS工艺兼容性，作为下一代非易失性存储器核心材料备受关注。然而，其极化切换机制的探索多依赖静态能垒分析，实际电场驱动下的瞬态键形成与协同动态机制尚未明确。本研究采用微调后的机器学习力场（MACEField），对无缺陷的理想HZO晶格开展电场诱导分子动力学（MD）模拟，成功动态复现了P-E滞回曲线，证实HZO的极化切换并非由传统简单位移模型（S:N/S:T模型）驱动，而是通过3配位氧（O3c）与4配位氧（O4c）的动态相互交换实现。对氧原子位移轨迹的分析显示，该路径伴随源于瞬态阳离子-氧键形成的独特“迂回”行为；此外，研究还发现一种“内部自补偿机制”，即配位数变化伴随的局部体积膨胀与收缩可在晶胞内有效抵消。这些发现从动态角度为HZO长期区别于传统钙钛矿铁电体却缺乏原子级解释的、无宏观应变即可维持稳定极化切换的优异性能提供了微观物理起源，表明保持协同O3c/O4c交换路径的完整性，而非最小化单个原子位移，是下一代铁电存储器耐久性与可扩展性的关键设计原则。
英文摘要
Hafnium zirconium oxide (HZO) has attracted significant attention as a core material for next-generation non-volatile memories due to its excellent ferroelectricity in the ultra-thin film regime and its CMOS process compatibility. However, the exploration of its polarization switching mechanism has predominantly relied on static energy barrier analyses, leaving the transient bond formation and cooperative dynamic mechanisms under actual electric field driving unresolved. In this study, we performed Electric-Field-Induced MD simulations on a defect-free ideal HZO lattice using a fine-tuned machine learning force field (MACEField). As a result, we successfully reproduced the P-E hysteresis loop dynamically and demonstrated that the polarization switching in HZO is driven not by conventional simple displacement models (S:N/S:T models), but by the dynamic mutual exchange of 3-coordinated oxygen (O3c) and 4-coordinated oxygen (O4c). Analysis of the oxygen atom displacement trajectories revealed that this pathway is accompanied by a unique "detour" behavior originating from transient cation-oxygen bond formation. Furthermore, we identified an "internal self-compensation mechanism" in which the local volumetric expansion and contraction accompanying the coordination number changes are effectively offset within the cell. These findings provide, from a dynamic perspective, a microscopic physical origin of for HZO's exceptional ability to sustain stable polarization switching without macroscopic strain, a property that has long distinguished HZO from conventional perovskite ferroelectrics yet lacked atomistic explanation. These findings suggest that preserving the integrity of cooperative O3c/O4c exchange pathways, rather than minimizing individual atomic displacements, is the key design principle for endurance and scalability in next-generation ferroelectric memories.
