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Tunable fragile topology in Floquet systems

TitleTunable fragile topology in Floquet systems
Publication TypeJournal Article
Year of Publication2021
AuthorsR-X. Zhang, and Z-C. Yang
JournalPhys. Rev. B
Date Publishedmar

We extend the notion of fragile topology to periodically driven systems. We demonstrate driving-induced fragile topology in two different models, namely, the Floquet honeycomb model and the Floquet pi-flux square-lattice model. In both cases, we discover a rich phase diagram that includes Floquet fragile topological phases protected by crystalline rotation or mirror symmetries, Floquet Chern insulators, and trivial atomic phases, with distinct boundary features. Remarkably, the transitions between different phases can be feasibly achieved by simply tuning the driving amplitudes, which is a unique feature of driving-enabled topological phenomena. Moreover, corner-localized fractional charges are identified as a “smoking-gun” signal of fragile topology in our systems. Our work paves the way for studying and realizing fragile topology in Floquet systems.