铁电氧化铪中填隙掺杂诱导矫顽场降低的起源
Origin of Interstitial Doping Induced Coercive Field Reduction in Ferroelectric Hafnia
AI总结：
该研究通过密度泛函理论、深度势分子动力学模拟和高通量计算，揭示了填隙掺杂降低铁电氧化铪矫顽场的原子尺度机制，并筛选出可有效降低矫顽场的填隙掺杂元素。
摘要：
基于氧化铪的铁电材料在非易失性铁电存储器件中具有广阔前景。然而，极化翻转所需的高矫顽场仍然是其实际应用的主要障碍。在含有填隙Hf(Zr)掺杂原子的铁电Hf(Zr)$_{1+x}$O$_2$薄膜中，已实现了矫顽场的显著降低 [Science 381, 558 (2023)]，这为矫顽场优化提供了一种较少探索的策略。在密度泛函理论计算的支持下，我们证明具有中等浓度填隙Hf掺杂原子的$Pca2_1$相，而非最初假设的菱方相，可以作为解释实验观测的最小模型。大规模深度势分子动力学模拟表明，填隙缺陷通过促进类似$Pbcn$的可移动180$^\circ$畴壁来促进极化反转。简单的预极化处理可以将翻转场降低至1 MV/cm以下，并实现亚纳秒时间尺度的翻转。高通量计算揭示了翻转势垒与掺杂原子尺寸之间的负相关关系，并确定了几种有前景的填隙掺杂原子用于降低矫顽场。
英文摘要：
Hafnia-based ferroelectrics hold promise for nonvolatile ferroelectric memory devices. However, the high coercive field required for polarization switching remains a prime obstacle to their practical applications. A notable reduction in coercive field has been achieved in ferroelectric Hf(Zr)$_{1+x}$O$_2$ films with interstitial Hf(Zr) dopants [Science 381, 558 (2023)], suggesting a less-explored strategy for coercive field optimization. Supported by density functional theory calculations, we demonstrate the $Pca2_1$ phase, with a moderate concentration of interstitial Hf dopants, serves as a minimal model to explain the experimental observations, rather than the originally assumed rhombohedral phase. Large-scale deep potential molecular dynamics simulations suggest that interstitial defects promote the polarization reversal by facilitating $Pbcn$-like mobile 180$^\circ$ domain walls. A simple pre-poling treatment could reduce the switching field to less than 1 MV/cm and enable switching on a subnanosecond timescale. High-throughput calculations reveal a negative correlation between the switching barrier and dopant size and identify a few promising interstitial dopants for coercive field reduction.
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