Li Chang-An, Fu Bo, Hu Zi-Ang, Li Jian, Shen Shun-Qing
School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China.
Institute of Natural Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China.
Phys Rev Lett. 2020 Oct 16;125(16):166801. doi: 10.1103/PhysRevLett.125.166801.
We investigate disorder-driven topological phase transitions in quantized electric quadrupole insulators in two dimensions. We show that chiral symmetry can protect the quantization of the quadrupole moment q_{xy}, such that the higher-order topological invariant is well defined even when disorder has broken all crystalline symmetries. Moreover, nonvanishing q_{xy} and consequent corner modes can be induced from a trivial insulating phase by disorder that preserves chiral symmetry. The critical points of such topological phase transitions are marked by the occurrence of extended boundary states even in the presence of strong disorder. We provide a systematic characterization of these disorder-driven topological phase transitions from both bulk and boundary descriptions.
我们研究了二维量子化电四极绝缘体中无序驱动的拓扑相变。我们表明，手征对称性可以保护四极矩(q_{xy})的量子化，使得即使无序破坏了所有晶体对称性，高阶拓扑不变量仍能很好地定义。此外，保持手征对称性的无序可以从平凡绝缘相诱导出非零的(q_{xy})以及随之产生的角模式。即使在强无序存在的情况下，这种拓扑相变的临界点也以扩展边界态的出现为标志。我们从体和边界描述两方面对这些无序驱动的拓扑相变进行了系统的表征。
