论文标题
$ n $储藏的su-schrieffer-heeger链的拓扑阶段通过系统破裂
Cataloging topological phases of $N$-stacked Su-Schrieffer-Heeger chains by a systematic breaking of symmetries
论文作者
论文摘要
研究了具有$ n $储存的su-schrieffer-heeger(SSH)链的弱拓扑绝缘子的二维(2D)模型。这项研究以一个基本模型开头,并保留了所有基本对称性(手性,时间反转和颗粒孔)。通过系统地破坏系统的对称性,在该模型中引入了不同的拓扑阶段。通过在系统中引入不同的键(跳术语)来打破对称性。首先,手性对称性通过在每个子晶格中引入跳跃或静物内跳的跳跃而被打破,在该跳动中,子晶格的跳跃强度在幅度上相等,但在符号中相反。然后,遵循Haldane,通过以虚构的数字替换真实的内部内部效果跳跃强度,而不会改变幅度,就会打破时间逆转(TR)对称性。我们发现打破手性和TR对称对于弱拓扑绝缘子成为Chern绝缘子至关重要。这些模型表现出非平凡的拓扑结构,Chern Number $ C = \ pm 1 $。系统中粒子孔(pH)对称性的保留促进了$ C $的分析计算,这与系统中数值观察到的拓扑相变的一致。还观察到了一类有趣的具有$ C = 0 $的拓扑非平地系统,其中非平凡性通过量化和分数2D Zak阶段识别。最后,通过引入不平等的弹药内跳强度的振幅,而pH对称性在系统中被损坏,而相等的内部内部跳动跳高强度可确保保留反演对称性。我们研究了拓扑相变中pH和反转对称性的相互作用。还提出了有关该模型可能实现的实验实现的讨论。
Two-dimensional (2D) model of a weak topological insulator with $N$-stacked Su-Schrieffer-Heeger (SSH) chain is studied. This study starts with a basic model with all the fundamental symmetries (chiral, time-reversal, and particle-hole) preserved. Different topological phases are introduced in this model by systematically breaking the system's symmetries. The symmetries are broken by introducing different bonds (hopping terms) in the system. First, the chiral symmetry is broken by introducing hopping within each sub-lattice or intra-sub-lattice hopping, where the hopping strengths of the sub-lattices are equal in magnitudes but opposite in sign. Then, following Haldane, the time-reversal (TR) symmetry is broken by replacing the real intra-sub-lattice hopping strengths with imaginary numbers without changing the magnitudes. We find that breaking chiral and TR symmetries are essential for the weak topological insulator to be a Chern insulator. These models exhibit nontrivial topology with the Chern number $C = \pm 1$. The preservation of the particle-hole (PH) symmetry in the system facilitates an analytical calculation of $C$, which agrees with the numerically observed topological phase transition in the system. An interesting class of topologically nontrivial systems with $C=0$ is also observed, where the non-triviality is identified by quantized and fractional 2D Zak phase. Finally, the PH symmetry is broken in the system by introducing unequal amplitudes of intra-sub-lattice hopping strengths, while the equal intra-sub-lattice hopping strengths ensures the preservation of the inversion symmetry. We investigate the interplay of the PH and the inversion symmetries in the topological phase transition. A discussion on the possible experimental realizations of this model is also presented.