2021/02/24 by Zhang-Zhao Yang, Yang, Zhang-Zhao, An-Yang Guan +7
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Applied Physics (physics.app-ph) #FOS: Physical sciences #Graphene research and applications #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2102.12234
openalex publication_date 2021/02/24 · openalex created_date 2021/03/01 · openalex updated_date 2026/07/28
The Su-Schrieffer-Heeger (SSH) model on a two-dimensional square lattice has been considered as a significant platform for studying topological multipole insulators. However, due to the highly-degenerate bulk energy bands protected by C4v and chiral symmetry, the discussion of the zero-energy topological corner states and the corresponding physical realization have been rarely presented. In this work, by tuning the hopping terms to break C4v symmetry down to C2v symmetry but with the topological phase invariant, we show that the degeneracies can be removed and a complete band gap can be opened, which provides robust protection for the spectrally isolated zero-energy corner states. Meanwhile, we propose a rigorous acoustic crystalline insulator and therefore these states can be observed directly. Our work reveals the topological properties of the robust zero-energy states, and provides a new way to explore novel topological phenomena.