Accidental degeneracy of double Dirac cones in a phononic crystal
Abstract
Artificial honeycomb lattices with Dirac cone dispersion provide a macroscopic platform to study the massless Dirac quasiparticles and their novel geometric phases. In this paper, a quadruple-degenerate state is achieved at the center of Brillouin zone (BZ) in a two-dimensional honeycomb lattice phononic crystal, which is a result of accidental degeneracy of two double-degenerate states. In the vicinity of the quadruple-degenerate state, the dispersion relation is linear. Such quadruple degeneracy is analyzed by rigorous representation theory of groups. Using method, a reduced Hamiltonian is obtained to describe the linear Dirac dispersion relations of such quadruple-degenerate state, which is well consistent with the simulation results. Near such accidental degeneracy, we observe some unique wave propagating properties, such as defect insensitive propagating character and Talbot effect.
Keywords
Cite
@article{arxiv.1402.2154,
title = {Accidental degeneracy of double Dirac cones in a phononic crystal},
author = {Ze-Guo Chen and Xu Ni and Ying Wu and Cheng He and Xiao-Chen Sun and Li-Yang Zheng and Ming-Hui Lu and Yan-Feng Chen},
journal= {arXiv preprint arXiv:1402.2154},
year = {2014}
}
Comments
24 pages, 7 figures and 1 table