Accidental degeneracy of double Dirac cones in a phononic crystal

Ze-guo Chen, Xu Ni, Ying Wu, Cheng He, Xiao-Chen Sun, Li-Yang Zheng, Ming-Hui Lu, Yan-Feng Chen

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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 the Brillouin zone 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 this quadruple-degenerate state, which is well consistent with the simulation results. Near such accidental degeneracy, we observe some unique properties in wave propagating, such as defect-insensitive propagating character and the Talbot effect.
Original languageEnglish (US)
JournalScientific Reports
Volume4
Issue number1
DOIs
StatePublished - Apr 9 2014

ASJC Scopus subject areas

  • General

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