论文标题
手性狄拉克超导体：二阶和边界拓扑
Chiral Dirac Superconductors: Second-order and Boundary-obstructed Topology
论文作者
论文摘要
我们分析了手性$ {p}+i {p} $超导体的拓扑特性，用于二维金属/半学和四个狄拉克点。已经提出了这样的系统来实现二阶拓扑超导和主机角模式。我们表明，使用额外的$ \ mathsf {c} _4 $旋转对称性，该系统处于固有的高阶拓扑超导体阶段，并且具有较低和更自然的$ \ Mathsf {c} _2 _2 $对称性，是在边界上吸引的拓扑超管制阶段。边界拓扑阻塞受到散装散布间隙的保护。但是，我们表明，尽管存在粒子孔对称性，但众所周知的嵌套威尔森环路通常是未量化的，因此失败了。取而代之的是，我们表明，可以使用替代缺陷分类方法来表征高阶拓扑和边界式拓扑结构，其中有限样本的角落被视为空间填充汉密尔顿的缺陷。我们将“ Dirac+$（{p}+i {p}）$”建立为二阶拓扑超导性的足够条件。
We analyze the topological properties of a chiral ${p}+i{p}$ superconductor for a two-dimensional metal/semimetal with four Dirac points. Such a system has been proposed to realize second-order topological superconductivity and host corner Majorana modes. We show that with an additional $\mathsf{C}_4$ rotational symmetry, the system is in an intrinsic higher-order topological superconductor phase, and with a lower and more natural $\mathsf{C}_2$ symmetry, is in a boundary-obstructed topological superconductor phase. The boundary topological obstruction is protected by a bulk Wannier gap. However, we show that the well-known nested-Wilson loop is in general unquantized despite the particle-hole symmetry, and thus fails as a topological invariant. Instead, we show that the higher-order topology and boundary-obstructed topology can be characterized using an alternative defect classification approach, in which the corners of a finite sample is treated as a defect of a space-filling Hamiltonian. We establish "Dirac+$({p}+i{p})$" as a sufficient condition for second-order topological superconductivity.
