Realizing type-III acoustic Dirac cones with the staggered Mielke model
Phys. Rev. B 113, 014301 – Published 5 January, 2026
DOI: https://doi.org/10.1103/9bsk-2jbt
Abstract
Dirac cones featuring linearly tilted band diagrams can be classified into type I, II, and III based on their degree of tilting. Type-III Dirac cones combining flat and linear dispersion have been largely unexplored in the acoustic domain. The Mielke model stands out as a potential candidate for supporting type-III Dirac cones. However, an experimentally feasible scheme for realizing the Mielke model still remains elusive. Here, we propose an acoustic implementation of the staggered Mielke model, which hosts type-III Dirac cones arising from flat band. By tuning onsite staggered frequency, we demonstrate the emergence, movement, and merging of these type-III Dirac cones at the Brillouin-zone boundary. We also observe exotic edge states connecting the type-III Dirac cones in the acoustic metamaterial. These results pave the way for experimentally investigating type-III acoustic Dirac cones and examining their behaviors, and thus set a new paradigm for manipulation of acoustic waves.
