Low‐dimensional structures comprised of ferroelectric (FE) PbTiO₃ (PTO) and quantum paraelectric SrTiO₃ (STO) are hosts to complex polarization textures such as polar waves, flux‐closure domains, and polar skyrmion phases. Density functional theory (DFT) simulations can provide insight into this order, but are limited by the computational effort required. Within DFT, the novel multi‐site support function method is used to reduce the solution time for the electronic groundstate whilst preserving high accuracy. This allows for large‐scale simulations of PTO films on STO substrates with system sizes >2000 atoms. In the ultrathin limit, the polar wave texture with cylindrical chiral bubbles emerges as an intermediate phase between full‐flux‐closure domains and in‐plane polarization. This is driven by an internal bias field born of the compositionally broken inversion symmetry in the [001] direction. Manipulation of this built‐in field informs a new principle of design for control over chiral order on the nanoscale through the careful choice of substrate, surface termination, or use of overlayers. Antiferrodistortive (AFD) order locally interacts with these polar textures giving rise to strong FE/AFD coupling at the PbO terminated surface driving a $p(2\times \mathrm{\Lambda })$ surface reconstruction. This offers another pathway for the local control of ferroelectricity.

中文翻译：

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第一性原理的极性形态：SrTiO3基底上的PbTiO3膜和p（2×Λ）表面重构

由铁电（FE）PbTiO ₃（PTO）和量子顺电SrTiO ₃组成的低维结构（STO）是复杂极化纹理的宿主，例如极化波，通量封闭域和极化天生离子相。密度泛函理论（DFT）仿真可以提供对此顺序的见解，但受到所需计算量的限制。在DFT中，新颖的多站点支持功能方法用于减少电子基态的求解时间，同时保持高精度。这允许在系统尺寸> 2000原子的STO基板上进行PTO薄膜的大规模仿真。在超薄极限内，带有圆柱形手性气泡的极性波纹理作为全通量封闭域和面内极化之间的中间相出现。这是由内部偏置场驱动的，该内部偏置场是在[001]方向上因成分破坏了反演对称性而产生的。通过谨慎选择基材，表面端接或使用覆盖层，对该内置字段的操作为控制纳米级手性顺序的设计提供了新原理。反铁畸变（AFD）顺序与这些极性纹理局部相互作用，从而在PbO终止的表面上产生强的FE / AFD耦合，从而驱动$p（2\times \mathrm{\Lambda }）$表面重建。这为铁电的局部控制提供了另一条途径。