Hybrid-Order Topological Insulators in a Phononic Crystal

作者：Yang, Yating; Lu, Jiuyang; Yan, Mou; Huang, Xueqin^*; Deng, Weiyin^*; Liu, Zhengyou^*

来源：Physical Review Letters, 2021, 126(15): 156801.

DOI：10.1103/PhysRevLett.126.156801

Topological phases, including the conventional first-order and higher-order topological insulators and semimetals, have emerged as a thriving topic in the fields of condensed-matter physics and materials science. Usually, a topological insulator is characterized by a fixed order topological invariant and exhibits associated bulk-boundary correspondence. Here, we realize a new type of topological insulator in a bilayer phononic crystal, which hosts simultaneously the first-order and second-order topologies, referred to here as the hybrid-order topological insulator. The one-dimensional gapless helical edge states, and zero-dimensional corner states coexist in the same system. The new hybrid-order topological phase may produce novel applications in topological acoustic devices.

• 单位
  武汉大学