Corner states in a second-order mechanical topological insulator

Georgios Theocharis (1) , Chun-Wei Chen , Rajesh Chaunsali (1) , Johan Christensen , Jinkyu Yang

1 LAUM - Laboratoire d'Acoustique de l'Université du Mans

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.

Domaines: Physique [physics]

Georgios Theocharis, Chun-Wei Chen, Rajesh Chaunsali, Johan Christensen, Jinkyu Yang. Corner states in a second-order mechanical topological insulator. Communications Materials, 2021, 2 (1), ⟨10.1038/s43246-021-00170-x⟩. ⟨hal-03446717⟩