Synthetic Weyl Points With Various Planar Symmetries In Phononic Crystals

We present a study on the existence of synthetic Weyl points with various planar symmetries in phononic crystals. We design a set of phononic crystals to display Weyl points at high-symmetry points with different symmetries in both square and honeycomb lattices. We demonstrate that, in a square lattice, double Weyl points are protected by C-4 rotation symmetry, while in a honeycomb lattice, they are protected by C-3 rotation symmetry. Additionally, we investigated the effects of symmetry on double Weyl points. The results indicate that double Weyl points would split into two single Weyl points along high-symmetry lines if we break the corresponding symmetries. The distributions of Weyl points in various symmetries are presented systematically. Finally, gapless surface states and the robust one-way acoustic transport in a square lattice are demonstrated in a double Weyl system. Published under license by AIP Publishing.