论文标题
单层砷葡萄染剂中的内在铁电和大型压电的预测
Prediction of intrinsic ferroelectricity and large piezoelectricity in monolayer arsenic chalcogenides
论文作者
论文摘要
表现出自发电化极化的二维材料对功能材料具有显着兴趣。然而，尽管从理论上预测了许多二维极性材料，但实验证实的二维铁电数量的数量仍然远远远远低于散装铁电。我们提供了有力的证据表明，PMN2 $ _1 $的砷硫化化剂的相位为$ _2 $ x $ x $ _3 $（x = S，SE和TE），其中包括最近隔离的单层orpiment，是固有的铁层，并且表现出强大的势力内电离。我们发现，与先前报道的铁电电子相比，我们发现计算出的能源壁垒，用于集体逆转电动极化或移动180 $^\ Circ $域壁是合理的。我们提出了一个高对称结构（带有PMMN空间组），通过软b $ _ {2U} $ phonon模式转换为铁电PMN2 $ _1 $ apeas。通过研究高对称性PMMN结构的其他软模式，我们确定了几个未发现的亚稳态多晶型物，包括具有可观的压电性的极相（具有P2 $ _1 $空间组）。
Two-dimensional materials that exhibit spontaneous electric polarization are of notable interest for functional materials. However, despite many two-dimensional polar materials are predicted in theory, the number of experimentally confirmed two-dimensional ferroelectrics are still far less than bulk ferroelectrics. We provide strong evidence that the Pmn2$_1$ phase of arsenic chalcogenides As$_2$X$_3$ (X=S, Se, and Te), which include the recently isolated monolayer orpiment, are intrinsic ferroelectrics and demonstrate strong in-plane piezoelectricity. We found the calculated energy barriers for collectively reversing the electric polarization or moving a 180$^\circ$ domain wall are reasonable compared to previously reported ferroelectrics. We propose a high-symmetry structure (with Pmmn space group) transforms into the ferroelectric Pmn2$_1$ phase by a soft B$_{2u}$ phonon mode. By studying other soft modes of the high-symmetry Pmmn structure, we identify several undiscovered metastable polymorphs, including a polar phase (with a P2$_1$ space group) with sizable piezoelectricity.
