Prediction of a topological p plus ip excitonic insulator with parity anomaly
Prediction of a topological p plus ip excitonic insulator with parity anomaly
复制标题
具有奇偶校验异常的拓扑 p 加 ip 激子绝缘体的预测
DOI：
10.1038/s41467-018-08203-9
复制
发表时间：
2019
影响因子：
16.6
通讯作者：
Xing D Y
中科院分区：
文献类型：
--
作者：
Wang Rui;Erten Onur;Wang Baigeng;Xing D Y
激子绝缘体是由电子和空穴对相干凝结成类似BCS状态而形成的绝缘态。各向同性空间波函数通常被认为是激子凝聚体，因为半导体中电子和空穴之间的吸引相互作用通常会产生 tos 波激子。在这里，我们提出了一种新型激子绝缘体，其具有 p+ip 对称性的有序参数，并具有手性陈数 Cc= 1/2 的特征。这种状态显示出奇偶校验异常，从而产生两种新颖的拓扑特性：缺陷处带有 e/2 电荷的分级激发和自发面内磁化。拓扑绝缘体表面态是实现拓扑激子绝缘体的一个有前景的平台。通过自旋动量锁定，带间光泵浦可以对表面电子进行重新归一化，并驱动系统达到所提出的 p+ipin 稳定性。
Excitonic insulators are insulating states formed by the coherent condensation of electron and hole pairs into BCS-like states. Isotropic spatial wave functions are commonly considered for excitonic condensates since the attractive interaction among the electrons and the holes in semiconductors usually leads tos-wave excitons. Here, we propose a new type of excitonic insulator that exhibits order parameter withp+ipsymmetry and is characterized by a chiral Chern numberCc= 1/2. This state displays the parity anomaly, which results in two novel topological properties: fractionalized excitations with e/2 charge at defects and a spontaneous in-plane magnetization. The topological insulator surface state is a promising platform to realize the topological excitonic insulator. With the spin-momentum locking, the interband optical pumping can renormalize the surface electrons and drive the system towards the proposedp+ipinstability.