The molecular dynamics method based on the shell model is used to investigate the polarization configuration evolution in compressed BaTiO3 nanofilms with oxygen vacancy lattices of different volume fractions and positions. A clockwise closure domain surrounding a head-to-head domain is observed for a single oxygen vacancy nanofilm. With an increasing oxygen vacancy fraction, the closure domain around the vacancy becomes larger and gradually transforms its rotation direction from clockwise to counterclockwise. Inside the vacancy, except for the head-to-head domain remaining unchanged, the domain changes from a random configuration to a clockwise vortex, and finally to a segmented strip polydomain with 90°- and 180°-domain walls. For a single oxygen vacancy, its location region where the closure domain can occur is obtained, and the model center is a favored site for clockwise vortex nucleation. The closure domain partly changes its orientation if the oxygen vacancy shifts off the model center. In addition, homogeneous closure domains can occur when the vacancy changes its location within a small area. This study demonstrates the feasibility of tuning this kind of closure domain in ferroelectric nanofilms through external loadings and oxygen vacancies. This could be instructive to develop novel nanoscale memories and logic devices.

中文翻译：

---

压缩 BaTiO3 纳米膜中氧空位引起的奇异闭合域

使用基于壳模型的分子动力学方法研究了具有不同体积分数和位置的氧空位晶格的压缩 BaTiO3 纳米薄膜的极化构型演变。对于单个氧空位纳米膜，观察到围绕头对头域的顺时针闭合域。随着氧空位分数的增加，空位周围的闭合域变大并逐渐将其旋转方向从顺时针方向转变为逆时针方向。在空位内部，除了头对头域保持不变外，域从随机配置变为顺时针涡旋，最后变为具有 90° 和 180° 畴壁的分段条状多畴。对于单个氧空位，得到其可能出现闭合域的位置区域，模型中心是顺时针涡旋形核的有利位置。如果氧空位偏离模型中心，闭合域会部分改变其方向。此外，当空位在小区域内改变其位置时，可能会出现同质封闭域。这项研究证明了通过外部负载和氧空位调整铁电纳米膜中这种封闭域的可行性。这对于开发新型纳米级存储器和逻辑器件可能具有指导意义。这项研究证明了通过外部负载和氧空位调整铁电纳米膜中这种封闭域的可行性。这对于开发新型纳米级存储器和逻辑器件可能具有指导意义。这项研究证明了通过外部负载和氧空位调整铁电纳米膜中这种封闭域的可行性。这对于开发新型纳米级存储器和逻辑器件可能具有指导意义。