arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2106.03595cond-mat.mes-hallquant-ph
收藏

一维双带绝缘体的轨道嵌入与拓扑

Orbital embedding and topology of one-dimensional two-band insulators

J. -N. Fuchs, F. Piéchon

摘要:

能带绝缘体的拓扑不变量通常被假设为只依赖于轨道之间的连通性,而不依赖于它们的胞内位置(轨道嵌入),这是紧束缚描述中的一个单独的信息。例如,在二维空间中,轨道嵌入会改变Berry曲率,但不会改变Chern数。在这里,我们考虑一维反演对称绝缘体分类的$\mathbb{Z}_2$拓扑不变$\vartheta=0$或$π$,相关的Zak阶段,并表明,$\vartheta$至关重要地依赖于轨道嵌入。我们研究了三种具有键、位和混合反转的双带模型:Su-Schrieffer-Heeger模型(SSH)、电荷密度波模型(CDW)和Shockley模型。SSH(或CDW)模型与$\vartheta=0$(分别为:$π$)。然而,肖克利模型的特征在于$\vartheta=0$和$π$之间的拓扑相变。关键的区别在于每个晶胞的两个轨道是在相同还是不同的位置。

英文摘要:

The topological invariants of band insulators are usually assumed to depend only on the connectivity between orbitals and not on their intra-cell position (orbital embedding), which is a separate piece of information in the tight-binding description. For example, in two dimensions, the orbital embedding is known to change the Berry curvature but not the Chern number. Here, we consider one-dimensional inversion-symmetric insulators classified by a $\mathbb{Z}_2$ topological invariant $\vartheta=0$ or $π$, related to the Zak phase, and show that $\vartheta$ crucially depends on orbital embedding. We study three two-band models with bond, site or mixed inversion: the Su-Schrieffer-Heeger model (SSH), the charge density wave model (CDW) and the Shockley model. The SSH (resp. CDW) model is found to have a unique phase with $\vartheta=0$ (resp. $π$). However, the Shockley model features a topological phase transition between $\vartheta=0$ and $π$. The key difference is whether the two orbitals per unit cell are at the same or different positions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑