Geometric phase and band inversion in periodic acoustic systems

Meng Xiao, Guancong Ma, Zhiyu Yang, Ping Sheng, Z. Q. Zhang, C. T. Chan*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

520 Citations (Scopus)


The geometric-phase concept has far-reaching implications in many branches of physics. The geometric phase that specifically characterizes the topological property of bulk bands in one-dimensional periodic systems is known as the Zak phase. Recently, it has been found that topological notions can also characterize the topological phase of mechanical isostatic lattices. Here, we present a theoretical framework and two experimental methods to determine the Zak phase in a periodic acoustic system. We constructed a phononic crystal with a topological transition point in the acoustic band structure where the band inverts and the Zak phase in the bulk band changes following a shift in system parameters. As a consequence, the topological characteristics of the bandgap change and interface states form at the boundary separating two phononic crystals having different bandgap topological characteristics. Such acoustic interface states with large sound intensity enhancement are observed at the phononic crystal interfaces.

Original languageEnglish
Pages (from-to)240-244
Number of pages5
JournalNature Physics
Issue number3
Publication statusPublished - Mar 2015

Scopus Subject Areas

  • Physics and Astronomy(all)


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