Helical Topological Edge States in a Quadrupole Phase
Helical Topological Edge States in a Quadrupole Phase
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DOI：
10.1103/physrevlett.122.086804
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发表时间：
2019-03-01
影响因子：
8.6
通讯作者：
Wakabayashi, Katsunori
中科院分区：
文献类型：
--
作者：
Liu, Feng;Deng, Hai-Yao;Wakabayashi, Katsunori
拓扑电四极矩是最近提出的一个概念，它将晶体的电极化理论推广到更高的阶数。这样的四极相支持位于边和角上的拓扑态。在这项工作中，我们证明了在蜂窝晶格的四极相中，通过利用与点群对称性有关的伪自旋自由度，出现了拓扑螺旋边态和伪自旋极化角态。此外，我们认为在(伪)自旋四极相中出现螺旋边态的一般条件是存在镜像对称性或时间反转对称性。我们的结果提供了一种不存在自旋-轨道耦合的产生拓扑螺旋边态的方法。
A topological electric quadrupole is a recently proposed concept that extends the theory of electric polarization of crystals to higher orders. Such a quadrupole phase supports topological states localized on both edges and corners. In this work, we show that in a quadrupole phase of a honeycomb lattice, topological helical edge states and pseudospin-polarized corner states appear by making use of a pseudospin degree of freedom related to point group symmetry. Furthermore, we argue that a general condition for the emergence of helical edge states in a (pseudo)spinful quadrupole phase is the existence of either mirror or time-reversal symmetry. Our results offer a way of generating topological helical edge states without spin-orbital couplings.