Corner states in a second-order mechanical topological insulator Articles uri icon


  • Chen, Chun Wei
  • Chaunsali, Rajesh
  • Theocharis, Georgios
  • Yang, Jinkyu

publication date

  • June 2021

start page

  • 1

end page

  • 6


  • 62


  • 2


  • Demonstration of topological boundary modes in elastic systems has attracted a great deal of attention over the past few years due to its unique protection characteristic. Recently, second-order topological insulators have been proposed in manipulating the topologically protected localized states emerging only at corners. Here, we numerically and experimentally study corner states in a two-dimensional phononic crystal, namely a continuous elastic plate with embedded bolts in a hexagonal pattern. We create interfacial corners by adjoining trivial and non-trivial topological configurations. Due to the rich interaction between the bolts and the continuous elastic plate, we find a variety of corner states of and devoid of topological origin. Strikingly, some of the corner states are not only highly-localized but also tunable. Taking advantage of this property, we experimentally demonstrate asymmetric corner localization in a Z-shaped domain wall. This finding could create interest in exploration of tunable corner states for the use of advanced control of wave localization.


  • Materials science and engineering
  • Physics


  • bolts; domain walls; electric insulators; topological insulators; corner localization