Reflection-Symmetric Second-Order Topological Insulators and Superconductors
Reflection-Symmetric Second-Order Topological Insulators and Superconductors
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DOI：
10.1103/physrevlett.119.246401
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发表时间：
2017-12-11
影响因子：
8.6
通讯作者：
Brouwer, Piet W.
中科院分区：
文献类型：
--
作者：
Langbehn, Josias;Peng, Yang;Brouwer, Piet W.
二阶拓扑绝缘体是具有带隙体和带隙晶界的晶体绝缘体，但在两个边界的交叉处具有拓扑保护的无隙态。在没有进一步空间对称性的情况下，Altland-Zirnbauer对称类中的五个允许在二维和三维中存在这样的二阶拓扑绝缘体。我们表明，反射对称性可以用来系统地产生二阶拓扑绝缘体和超导体的例子，虽然在角落（二维）或晶体边缘（三维）的拓扑保护状态继续存在，如果反射对称性被打破。具有破缺时间反转对称性的三维二阶拓扑绝缘体的霍尔电导量子化为e（2）/h。
Second-order topological insulators are crystalline insulators with a gapped bulk and gapped crystalline boundaries, but with topologically protected gapless states at the intersection of two boundaries. Without further spatial symmetries, five of the ten Altland-Zirnbauer symmetry classes allow for the existence of such second-order topological insulators in two and three dimensions. We show that reflection symmetry can be employed to systematically generate examples of second-order topological insulators and superconductors, although the topologically protected states at corners (in two dimensions) or at crystal edges (in three dimensions) continue to exist if reflection symmetry is broken. A three-dimensional secondorder topological insulator with broken time-reversal symmetry shows a Hall conductance quantized in units of e(2)/h.