Tailoring quadrupole topological insulators with periodic driving and disorder

The quadrupole topological insulator (QTI) has attracted intense studies as a prototype of symmetry-protected higher-order topological phases of matter with a quantized quadrupole moment. The realization of QTIs has been reported in various static settings with periodic structures. Here, we theoretically investigate topological phase transitions and establish the QTI phase in a periodically driven system with disorder. In the clean limit, the Floquet QTI phase emerges from a topologically trivial band structure driven by elliptically polarized irradiation. More strikingly, starting from a pure and static system with trivial topology, we unveil an intriguing QTI phase which necessitates the simultaneous presence of disorder and periodic driving. Furthermore, we reveal that particle-hole symmetry is sufficient to protect the QTI. Our work not only establishes a strategy to design QTIs but also enriches the symmetry-protected mechanism of higher-order topology.

Automated summary

This paper theoretically investigates topological phase transitions and establishes the quadrupole topological insulator (QTI) phase in a periodically driven system with disorder. The results show that the Floquet QTI phase can emerge from a topologically trivial band structure driven by elliptically polarized irradiation, and an intriguing QTI phase which necessitates the simultaneous presence of disorder and periodic driving can be revealed starting from a pure and static system with trivial topology. Furthermore, it is revealed that particle-hole symmetry is sufficient to protect the QTI.