We investigate the multidomain structures in the tetragonal and orthorhombic phases of ${\mathrm{BaTiO}}_3$ and the impact of the presence of domain walls on the intermediary phase transition. We focus on the change in the transition temperatures resulting from various types of domain walls and their coupling with an external electric field. We employ molecular dynamics simulations of an ab initio effective Hamiltonian in this study. After confirming that this model is applicable to multidomain configurations, we show that the phase-transition temperatures strongly depend on the presence of domains walls. Notably we show that elastic ${90}^{\circ }$ walls can strongly reduce thermal hysteresis. Further analysis shows that the change in transition temperatures can be attributed to two main factors: long-range monoclinic distortions induced by walls within domains and domain wall widths. We also show that the coupling with the field further facilitates the reduction of thermal hysteresis for orthorhombic ${90}^{\circ }$ walls, making this configuration attractive for future applications.

中文翻译：

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域对BaTiO3正交晶向四方过渡的影响：Anab初始定律

我们研究了四方相和正交相中的多畴结构 ${\mathrm{钛酸钡}}_3$以及畴壁的存在对中间相变的影响。我们关注于由于各种类型的畴壁及其与外部电场的耦合而导致的转变温度的变化。在这项研究中，我们采用了从头算有效的哈密顿量的分子动力学模拟。确认此模型适用于多域配置后，我们证明了相变温度强烈取决于域壁的存在。值得注意的是，我们表明${90}^{\circ }$墙壁可以大大降低热滞。进一步的分析表明，转变温度的变化可归因于两个主要因素：畴内壁引起的长期单斜畸变和畴壁宽度。我们还表明，与磁场的耦合进一步促进了正交晶系的热滞现象的减少${90}^{\circ }$ 墙，使这种配置对将来的应用具有吸引力。