Origin of Ferroelectric Domain Wall Alignment with Surface Trenches in Ultrathin Films.
Origin of Ferroelectric Domain Wall Alignment with Surface Trenches in Ultrathin Films.
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DOI：
10.1103/physrevlett.127.247601
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发表时间：
2021-04
影响因子：
8.6
通讯作者：
J. Baker;D. Bowler
中科院分区：
文献类型：
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作者：
J. Baker;D. Bowler
在超薄铁电(FE)薄膜和超晶格表面雕刻沟槽可以控制FE磁区壁(DWS)的取向和方向。通过利用DW-表面沟槽(ST)平行对准的现象，DW因成为电导体而闻名的系统现在只需使用标准光刻技术就可以成为有用的纳米电路。尽管有这种明确的应用，但导致排列现象的微观机制仍然难以捉摸。以PbTiO3超薄薄膜为模型系统，对多达5,136个原子进行了大规模密度泛函理论模拟。尽管我们预计会有多种影响因素，但我们发现平行的DW-ST排列可以很好地用这种排列方式来解释，这种排列的电偶极矩最好地恢复了薄膜的极性连续性。这些时刻保留了原始薄膜的极性纹理，从而最大限度地减少了ST诱导的去极化磁场。鉴于这一机制的普遍性，我们建议STS可以用来在各种Fe纳米结构中设计其他奇异的极性织构，正如本文中ST诱导的极性摆线调制的出现所支持的那样。我们的模拟也支持ST诱导的负应变的实验观察，这些应变被认为在排列机制中发挥了作用。
Engraving trenches on the surfaces of ultrathin ferroelectric (FE) films and superlattices promises control over the orientation and direction of FE domain walls (DWs). Through exploiting the phenomenon of DW-surface trench (ST) parallel alignment, systems where DWs are known for becoming electrical conductors could now become useful nanocircuits using only standard lithographical techniques. Despite this clear application, the microscopic mechanism responsible for the alignment phenomenon has remained elusive. Using ultrathin PbTiO_{3} films as a model system, we explore this mechanism with large scale density functional theory simulations on as many as 5,136 atoms. Although we expect multiple contributing factors, we show that parallel DW-ST alignment can be well explained by this configuration giving rise to an arrangement of electric dipole moments which best restore polar continuity to the film. These moments preserve the polar texture of the pristine film, thus minimizing ST-induced depolarizing fields. Given the generality of this mechanism, we suggest that STs could be used to engineer other exotic polar textures in a variety of FE nanostructures as supported by the appearance of ST-induced polar cycloidal modulations in this Letter. Our simulations also support experimental observations of ST-induced negative strains which have been suggested to play a role in the alignment mechanism.