Acoustic Type-II Weyl Nodes from Stacking Dimerized Chains

• Main Authors: Yang, Zhaoju, Zhang, Baile
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2017
• Subjects: Ultrasonics; Linear Acoustics
• Online Access: https://hdl.handle.net/10356/84041; http://hdl.handle.net/10220/42912
• Institution: Nanyang Technological University

Lorentz-violating type-II Weyl fermions, which were missed in Weyl’s prediction of nowadays classified type-I Weyl fermions in quantum field theory, have recently been proposed in condensed matter systems. The semimetals hosting type-II Weyl fermions offer a rare platform for realizing many exotic physical phenomena that are different from type-I Weyl systems. Here we construct the acoustic version of a type-II Weyl Hamiltonian by stacking one-dimensional dimerized chains of acoustic resonators. This acoustic type-II Weyl system exhibits distinct features in a finite density of states and unique transport properties of Fermi-arc-like surface states. In a certain momentum space direction, the velocity of these surface states is determined by the tilting direction of the type-II Weyl nodes rather than the chirality dictated by the Chern number. Our study also provides an approach of constructing acoustic topological phases at different dimensions with the same building blocks.