论文标题
耦合多扬链链中的拓扑阶段
Topological Phases in Coupled Polyyne Chains
论文作者
论文摘要
我们研究了几个对称的堆叠布置中耦合的平行多烯链的电子特性，即AA堆叠和堆叠AB，其中一个链（AA）的单个和三碳键与另一个链的单链（AA）和抗镇定（AB）。这两种布置都由紧密结合的汉密尔顿人描述，其参数是通过首先原理计算提供的低能量分散量来校准的，它属于BDI拓扑分类方案的类别。我们计算系统的所有三个拓扑阶段的拓扑不变性：一个用于AA堆叠的拓扑阶段，AB堆叠为2。在AA堆叠中，绝缘阶段和金属阶段都属于同一拓扑阶段。鉴于该模型在两个不同的绝缘阶段（通过横向应变分化）在两个不同的绝缘相中表现出两个不同的值。在此后来的堆叠中，尽管两个不同的拓扑阶段之间的过渡和间隙的闭合实际上是无法实现的，因此由于需要大量的横向应变。我们还显示了AA堆叠中存在4个非零的能量边缘模式，而AB堆叠的拓扑阶段之一中存在2个零能量边缘模式。
We study the electronic properties of coupled parallel Polyyne chains in a couple of symmetric stacking arrangements, namely the AA stacking and the stacking AB, with the single and triple carbon bonds of one chain aligned (AA) and anti-aligned (AB) with those of the other chain. Both these arrangements described by tight binding Hamiltonians, whose parameters are calibrated by matching low energy dispersion provided by first principle calculations, fall in the BDI class of topological classification scheme. We calculate the topological invariants for all the three topological phases of the system: one for the AA stacking and 2 for the AB one. In the AA stacking, both the insulating and the metallic phase belongs to the same topological phase. Whereas, the model exhibits two different values of the topological invariant in the two different insulating phases (structurally differentiated by transverse strain). In this later stacking though transition between two distinct topological phases with the closure of the gap is practically unachievable due requirement of high amount of transverse strain. We also show existence of 4 non-zero energy edge modes in the AA stacking and that of 2 zero energy edge modes in one of the topological phases for the AB stacking.
