Ideal Weyl phonons in telluride

Weyl nodes in momentum space of periodic lattices can result in many intriguing phenomena and have been actively studied in various systems recently, including electronic band in solid, photonic band in photonic crystal, phonon and acoustic spectra. The well-known case is the Weyl nodes of electronic band around Fermi level, which is called Weyl semimetal. The only available samples are TaAs family compounds. They are not ideal for characterizing the unique responses of Weyl nodes since they have other trivial bulk pockets at Fermi energy. Thus, searching for Weyl nodes with a clean isoenergic surface is highly demanded for studying the expected novel phenomena. In this work, we propose a phononic crystal, which have six pairs of Weyl nodes related with symmetrical operations and they are the only phonon at 3.22 terahertz. On the surface of this crystal, the isoenergic surface show very clean arc states.