论文标题
在有限温度下原子薄软铁膜的拓扑
Topology of atomically thin soft ferroelectric membranes at finite temperature
论文作者
论文摘要
2D铁电的二维（2D）结构转换的一个说法预测了从具有PNM2 $ _1 $对称的结构中的演变为具有Square P4/NMM对称性的结构，并且与实验证据一致，而另一种争论将矩形PNMM对称性转换为结构。此处提供了对这些模型中提出的假设的分析，有关这些转换的六个基本结果如下：（i）软音子模式在这些材料中产生旋转模式。 （ii）在最低的临界温度$ t_c $的情况下，转换为具有P4/NMM对称性的结构。 （iii）一个单向光学振动模式下的假设是2D转换是无根据的。 （iv）受到更大的约束，一系列的临界温度（$ t_c <t_c'<t_c''$）发生在从分子动力学计算中，NPT和NVT集合以单向振荡为模型。 （v）交换相关功能的选择会影响临界温度的估计。 （vi）至关重要的是，这些转换的正确物理图片是旋转模式通过涡旋的扩散将拓扑特征赋予2D变换的旋转模式。
One account of two-dimensional (2D) structural transformations in 2D ferroelectrics predicts an evolution from a structure with Pnm2$_1$ symmetry into a structure with square P4/nmm symmetry and is consistent with experimental evidence, while another argues for a transformation into a structure with rectangular Pnmm symmetry. An analysis of the assumptions made in these models is provided here, and six fundamental results concerning these transformations are contributed as follows: (i) Softened phonon modes produce rotational modes in these materials. (ii) The transformation to a structure with P4/nmm symmetry occurs at the lowest critical temperature $T_c$. (iii) The hypothesis that one unidirectional optical vibrational mode underpins the 2D transformation is unwarranted. (iv) Being successively more constrained, a succession of critical temperatures ($T_c<T_c'<T_c''$) occurs in going from molecular dynamics calculations with the NPT and NVT ensembles onto the model with unidirectional oscillations. (v) The choice of exchange-correlation functional impacts the estimate of the critical temperature. (vi) Crucially, the correct physical picture of these transformations is one in which rotational modes confer a topological character to the 2D transformation via the proliferation of vortices.
