论文标题
二维C2N及其衍生物中的二阶拓扑绝缘子
Second-Order Topological Insulator in Two-Dimensional C2N and Its Derivatives
论文作者
论文摘要
四极阶段作为一种新型的高阶拓扑阶段，在边界上表现出非平凡的无间隙状态，其尺寸低于两个尺寸。但是，迄今为止，在二维（2D）材料中尚未在实验中观察到这一阶段。在这项工作中，使用第一原理计算和紧密结合（TB）模型，我们建议实验合成的C2N是一个2D四极拓扑绝缘子，具有一维间隙边缘状态和零维的无差距角状态。发现C2N的大容量间隙为2.45 eV，边缘间隙为0.32 eV，使其成为显然在实验中显然呈现非平凡角状态的极好候选者。明确鉴定出角度对边缘疾病的鲁棒性。此外，还发现另外三种类似C2N的材料可容纳非平凡的四极相，其中包括实验合成的材料AZA融合的微孔聚合物（CMP）。我们目前的工作中提出的四个2D四极拓扑阶段为研究新的高阶拓扑特性提供了出色的候选者。
Quadrupole phase, as a novel high-order topological phase, exhibits nontrivial gapless states at the boundaries whose dimension is lower than bulk by two. However, this phase has not been observed experimentally in two-dimensional (2D) materials up to now. In this work, using first-principles calculations and tight-binding (TB) model, we propose that the experimentally synthesized C2N is a 2D quadrupole topological insulator with one-dimensional gapped edge states and zero-dimensional gapless corner states. C2N is found to have a large bulk gap of 2.45 eV and an edge gap of 0.32 eV, making it an excellent candidate to evidently present the nontrivial corner states in experiments. The robustness of the corner states against the edge disorders has been explicitly identified. Moreover, another three C2N-like materials are also found to host the nontrivial quadrupole phase including an experimentally synthesized material aza-fused microporous polymers (CMP). The four 2D quadrupole topological phases proposed in our present work provide excellent candidates for studying the novel high-order topological properties in future experiments.
