Non-Hermitian systems can exhibit exotic topological and localization properties. Here we elucidate the non-Hermitian effects on disordered topological systems using a nonreciprocal disordered Su-Schrieffer-Heeger model. We show that the non-Hermiticity can enhance the topological phase against disorders by increasing bulk gaps. Moreover, we uncover a topological phase which emerges under both moderate non-Hermiticity and disorders, and is characterized by localized insulating bulk states with a disorder-averaged winding number and zero-energy edge modes. Such topological phases induced by the combination of non-Hermiticity and disorders are dubbed non-Hermitian topological Anderson insulators. We reveal that the system has unique non-monotonous localization behavior and the topological transition is accompanied by an Anderson transition. These properties are general in other non-Hermitian models.

中文翻译：

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非Hermitian拓扑Anderson绝缘子

非Hermitian系统可以表现出奇异的拓扑和本地化特性。在这里，我们使用非可逆的无序Su-Schrieffer-Heeger模型阐明对无序拓扑系统的非Hermitian效应。我们表明，非高铁性可以通过增加体积间隙来增强抗病性的拓扑相。此外，我们发现了一种拓扑相，该相在适度的非赫米蒂性和无序状态下均会出现，并且其特征在于局部绝缘体态具有无序平均绕组数和零能边模。由非赫米蒂性和无序性的组合诱发的此类拓扑阶段称为非赫米特拓扑安德森绝缘子。我们揭示了该系统具有独特的非单调本地化行为，并且拓扑转变伴随着安德森转变。这些属性在其他非Hermitian模型中是通用的。