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Floquet second-order topological insulators in non-Hermitian systems

2021; American Physical Society; Volume: 103; Issue: 4 Linguagem: Inglês

10.1103/physrevb.103.l041115

2469-9977

Hong Wu, Baoqin Wang, Jun‐Hong An,

Photorefractive and Nonlinear Optics

Second-order topological insulator (SOTI) is featured with the presence of $(d\ensuremath{-}2)$-dimensional boundary states in $d$-dimension systems. The non-Hermiticity induced breakdown of bulk-boundary correspondence (BBC) and the periodic driving on systems generally obscure the description of non-Hermitian SOTI. To prompt the applications of SOTIs, we explore the role of periodic driving in controllably creating exotic non-Hermitian SOTIs both for 2D and 3D systems. A scheme to retrieve the BBC and a complete description to SOTIs via the bulk topology of such nonequilibrium systems are proposed. It is found that rich exotic non-Hermitian SOTIs with a widely tunable number of 2D corner states and 3D hinge states and a coexistence of the first- and second-order topological insulators are induced by the periodic driving. Enriching the family of topological phases, our result may inspire the exploration to apply SOTIs via tuning the number of corner/hinge states by the periodic driving.