原子尺度研究氦离子注入调控极化拓扑畴

铁电材料在精密驱动、热成像以及信息存储方面具有广泛应用。在铁电研究中，尺寸效应（铁电极化如何随尺寸变化）在基础研究及实际研究方面都广受关注。在纳米铁电结构中，低维度铁电涡旋态由于其拓扑特性以及在负电容器件中的应用潜力而成为近年来研究热点之一。氦离子注入可以模拟外太空 α 射线辐照下的应用场景。然而，在氦离子注入下，通量闭合畴的拓扑保护性与辐照耐受性及极化破坏机制尚无研究。研究此课题，对于太空场景下铁电非易失性存储器的应用至关重要。我们利用扫描透射电镜从原子尺度研究了通量闭合畴在经历氦离子辐照后的结构及涡旋构型变化。在 PbTiO3/SrTiO3 超晶格涡旋体系，随着注入剂量增加，我们首先发现极化涡旋态最初表现出辐照耐受性（1×1015 ions/cm2），随后发生 a 畴向 c 畴的转变（5×1015 ions/cm2）。紧接着，长程有序性被破坏，原涡旋中心处发生明显晶格畸变，并出现局部非晶化（1×1016 至 2×1016 ions/cm2）。最终非晶区域扩张至整个 PbTiO3 层乃至整个超晶格，直至完全破坏（5×1016 至1×1018 ions/cm2）。通过原子尺度的应力及极化分析，我们发现氦离子具有电荷注入和体积膨胀的双重作用，通过改变通量闭合畴的电荷及应力条件，从而调控畴结构以及产生辐照损伤。

本研究不仅扩大了对铁电通量闭合畴在复杂环境下行为的理解，同时也对其在存储领域的潜在应用提供了有意义的参考。未来的研究可能会继续探索在不同条件下通量闭合畴的转变和稳定性，为铁电拓扑结构的调控提供理论指导。

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